renamer.zig

const js_ast = bun.JSAst;
const bun = @import("root").bun;
const string = bun.string;
const Output = bun.Output;
const Global = bun.Global;
const Environment = bun.Environment;
const strings = bun.strings;
const MutableString = bun.MutableString;
const stringZ = bun.stringZ;
const default_allocator = bun.default_allocator;
const C = bun.C;
const std = @import("std");
const Ref = @import("./ast/base.zig").Ref;
const RefCtx = @import("./ast/base.zig").RefCtx;
const logger = bun.logger;
const JSLexer = @import("./js_lexer.zig");

pub const NoOpRenamer = struct {
    symbols: js_ast.Symbol.Map,
    source: *const logger.Source,

    pub fn init(symbols: js_ast.Symbol.Map, source: *const logger.Source) NoOpRenamer {
        return NoOpRenamer{ .symbols = symbols, .source = source };
    }

    pub const originalName = nameForSymbol;

    pub fn nameForSymbol(renamer: *NoOpRenamer, ref: Ref) string {
        if (ref.isSourceContentsSlice()) {
            return renamer.source.contents[ref.sourceIndex() .. ref.sourceIndex() + ref.innerIndex()];
        }

        const resolved = renamer.symbols.follow(ref);

        if (renamer.symbols.getConst(resolved)) |symbol| {
            return symbol.original_name;
        } else {
            Global.panic("Invalid symbol {s} in {s}", .{ ref, renamer.source.path.text });
        }
    }

    pub fn toRenamer(this: *NoOpRenamer) Renamer {
        return .{
            .NoOpRenamer = this,
        };
    }
};

pub const Renamer = union(enum) {
    NumberRenamer: *NumberRenamer,
    NoOpRenamer: *NoOpRenamer,
    MinifyRenamer: *MinifyRenamer,

    pub fn symbols(this: Renamer) js_ast.Symbol.Map {
        return switch (this) {
            inline else => |r| r.symbols,
        };
    }

    pub fn nameForSymbol(renamer: Renamer, ref: Ref) string {
        return switch (renamer) {
            inline else => |r| r.nameForSymbol(ref),
        };
    }

    pub fn originalName(renamer: Renamer, ref: Ref) ?string {
        return switch (renamer) {
            inline else => |r| r.originalName(ref),
        };
    }

    pub fn deinit(renamer: Renamer, allocator: std.mem.Allocator) void {
        switch (renamer) {
            .NumberRenamer => |r| r.deinit(),
            .MinifyRenamer => |r| r.deinit(allocator),
            else => {},
        }
    }
};

pub const SymbolSlot = struct {
    // Most minified names are under 15 bytes
    // Instead of allocating a string for every symbol slot
    // We can store the string inline!
    // But we have to be very careful of where it's used.
    // Or we WILL run into memory bugs.
    name: TinyString = TinyString{ .string = "" },
    count: u32 = 0,
    needs_capital_for_jsx: bool = false,

    pub const List = std.EnumArray(js_ast.Symbol.SlotNamespace, std.ArrayList(SymbolSlot));

    pub const InlineString = struct {
        bytes: [15]u8 = [_]u8{0} ** 15,
        len: u8 = 0,

        pub fn init(str: []const u8) InlineString {
            var this: InlineString = .{};
            this.len = @as(u8, @intCast(@min(str.len, 15)));
            for (this.bytes[0..this.len], str[0..this.len]) |*b, c| {
                b.* = c;
            }
            return this;
        }

        // do not make this *const or you will run into memory bugs.
        // we cannot let the compiler decide to copy this struct because
        // that would cause this to become a pointer to stack memory.
        pub fn slice(this: *InlineString) string {
            return this.bytes[0..this.len];
        }
    };

    pub const TinyString = union(enum) {
        inline_string: InlineString,
        string: string,

        pub fn init(input: string, allocator: std.mem.Allocator) !TinyString {
            if (input.len <= 15) {
                return TinyString{ .inline_string = InlineString.init(input) };
            } else {
                return TinyString{ .string = try allocator.dupe(u8, input) };
            }
        }

        // do not make this *const or you will run into memory bugs.
        // we cannot let the compiler decide to copy this struct because
        // that would cause this to become a pointer to stack memory.
        pub fn slice(this: *TinyString) string {
            return switch (this.*) {
                .inline_string => this.inline_string.slice(),
                .string => this.string,
            };
        }
    };
};

pub const MinifyRenamer = struct {
    reserved_names: bun.StringHashMapUnmanaged(u32),
    allocator: std.mem.Allocator,
    slots: SymbolSlot.List = undefined,
    top_level_symbol_to_slot: TopLevelSymbolSlotMap,
    symbols: js_ast.Symbol.Map,

    pub const TopLevelSymbolSlotMap = std.HashMapUnmanaged(Ref, usize, RefCtx, 80);

    pub fn init(
        allocator: std.mem.Allocator,
        symbols: js_ast.Symbol.Map,
        first_top_level_slots: js_ast.SlotCounts,
        reserved_names: bun.StringHashMapUnmanaged(u32),
    ) !*MinifyRenamer {
        const renamer = try allocator.create(MinifyRenamer);
        var slots = SymbolSlot.List.initUndefined();

        for (first_top_level_slots.slots.values, 0..) |count, ns| {
            slots.values[ns] = try std.ArrayList(SymbolSlot).initCapacity(allocator, count);
            slots.values[ns].items.len = count;
            @memset(slots.values[ns].items[0..count], SymbolSlot{});
        }

        renamer.* = MinifyRenamer{
            .symbols = symbols,
            .reserved_names = reserved_names,
            .slots = slots,
            .top_level_symbol_to_slot = TopLevelSymbolSlotMap{},
            .allocator = allocator,
        };

        return renamer;
    }

    pub fn deinit(this: *MinifyRenamer, allocator: std.mem.Allocator) void {
        for (&this.slots.values) |*val| {
            val.deinit();
        }
        this.reserved_names.deinit(allocator);
        this.top_level_symbol_to_slot.deinit(allocator);
        allocator.destroy(this);
    }

    pub fn toRenamer(this: *MinifyRenamer) Renamer {
        return .{
            .MinifyRenamer = this,
        };
    }

    pub fn nameForSymbol(this: *MinifyRenamer, _ref: Ref) string {
        const ref = this.symbols.follow(_ref);
        const symbol = this.symbols.get(ref).?;

        const ns = symbol.slotNamespace();
        if (ns == .must_not_be_renamed) {
            return symbol.original_name;
        }

        const i = symbol.nestedScopeSlot() orelse
            this.top_level_symbol_to_slot.get(ref) orelse
            return symbol.original_name;

        // This has to be a pointer because the string might be stored inline
        return this.slots.getPtr(ns).items[i].name.slice();
    }

    pub fn originalName(this: *MinifyRenamer, ref: Ref) ?string {
        _ = ref;
        _ = this;
        return null;
    }

    pub fn accumulateSymbolUseCounts(
        this: *MinifyRenamer,
        top_level_symbols: *StableSymbolCount.Array,
        symbol_uses: js_ast.Part.SymbolUseMap,
        stable_source_indices: []const u32,
    ) !void {
        var iter = symbol_uses.iterator();
        while (iter.next()) |value| {
            try this.accumulateSymbolUseCount(top_level_symbols, value.key_ptr.*, value.value_ptr.*.count_estimate, stable_source_indices);
        }
    }

    pub fn accumulateSymbolUseCount(
        this: *MinifyRenamer,
        top_level_symbols: *StableSymbolCount.Array,
        _ref: Ref,
        count: u32,
        stable_source_indices: []const u32,
    ) !void {
        var ref = this.symbols.follow(_ref);
        var symbol = this.symbols.get(ref).?;

        while (symbol.namespace_alias != null) {
            const ref_ = this.symbols.follow(symbol.namespace_alias.?.namespace_ref);
            if (ref_.eql(ref)) break;
            ref = ref_;
            symbol = this.symbols.get(ref_).?;
        }

        const ns = symbol.slotNamespace();
        if (ns == .must_not_be_renamed) return;

        if (symbol.nestedScopeSlot()) |i| {
            var slot = &this.slots.getPtr(ns).items[i];
            slot.count += count;
            if (symbol.must_start_with_capital_letter_for_jsx) {
                slot.needs_capital_for_jsx = true;
            }
            return;
        }

        try top_level_symbols.append(StableSymbolCount{
            .stable_source_index = stable_source_indices[ref.sourceIndex()],
            .ref = ref,
            .count = count,
        });
    }

    pub fn allocateTopLevelSymbolSlots(this: *MinifyRenamer, top_level_symbols: StableSymbolCount.Array) !void {
        for (top_level_symbols.items) |stable| {
            const symbol = this.symbols.get(stable.ref).?;
            var slots = this.slots.getPtr(symbol.slotNamespace());

            const existing = try this.top_level_symbol_to_slot.getOrPut(this.allocator, stable.ref);
            if (existing.found_existing) {
                var slot = &slots.items[existing.value_ptr.*];
                slot.count += stable.count;
                if (symbol.must_start_with_capital_letter_for_jsx) {
                    slot.needs_capital_for_jsx = true;
                }
            } else {
                existing.value_ptr.* = slots.items.len;
                try slots.append(SymbolSlot{
                    .count = stable.count,
                    .needs_capital_for_jsx = symbol.must_start_with_capital_letter_for_jsx,
                });
            }
        }
    }

    pub fn assignNamesByFrequency(this: *MinifyRenamer, name_minifier: *js_ast.NameMinifier) !void {
        var name_buf = try std.ArrayList(u8).initCapacity(this.allocator, 64);
        defer name_buf.deinit();

        var sorted = SlotAndCount.Array.init(this.allocator);
        defer sorted.deinit();

        inline for (comptime std.enums.values(js_ast.Symbol.SlotNamespace)) |ns| {
            var slots = this.slots.getPtr(ns);
            sorted.clearRetainingCapacity();
            try sorted.ensureUnusedCapacity(slots.items.len);
            sorted.items.len = slots.items.len;

            for (sorted.items, slots.items, 0..) |*elem, slot, i| {
                elem.* = SlotAndCount{
                    .slot = @as(u32, @intCast(i)),
                    .count = slot.count,
                };
            }
            std.sort.pdq(SlotAndCount, sorted.items, {}, SlotAndCount.lessThan);

            var next_name: isize = 0;

            for (sorted.items) |data| {
                var slot = &slots.items[data.slot];

                try name_minifier.numberToMinifiedName(&name_buf, next_name);
                next_name += 1;

                // Make sure we never generate a reserved name. We only have to worry
                // about collisions with reserved identifiers for normal symbols, and we
                // only have to worry about collisions with keywords for labels. We do
                // not have to worry about either for private names because they start
                // with a "#" character.
                switch (comptime ns) {
                    .default => {
                        while (this.reserved_names.contains(name_buf.items)) {
                            try name_minifier.numberToMinifiedName(&name_buf, next_name);
                            next_name += 1;
                        }

                        if (slot.needs_capital_for_jsx) {
                            while (name_buf.items[0] >= 'a' and name_buf.items[0] <= 'z') {
                                try name_minifier.numberToMinifiedName(&name_buf, next_name);
                                next_name += 1;
                            }
                        }
                    },
                    .label => {
                        while (JSLexer.Keywords.has(name_buf.items)) {
                            try name_minifier.numberToMinifiedName(&name_buf, next_name);
                            next_name += 1;
                        }
                    },
                    .private_name => {
                        try name_buf.insert(0, '#');
                    },
                    else => {},
                }

                slot.name = SymbolSlot.TinyString.init(name_buf.items, this.allocator) catch unreachable;
            }
        }
    }
};

pub fn assignNestedScopeSlots(allocator: std.mem.Allocator, module_scope: *js_ast.Scope, symbols: []js_ast.Symbol) js_ast.SlotCounts {
    var slot_counts = js_ast.SlotCounts{};
    var sorted_members = std.ArrayList(u32).init(allocator);
    defer sorted_members.deinit();

    // Temporarily set the nested scope slots of top-level symbols to valid so
    // they aren't renamed in nested scopes. This prevents us from accidentally
    // assigning nested scope slots to variables declared using "var" in a nested
    // scope that are actually hoisted up to the module scope to become a top-
    // level symbol.
    const valid_slot: u32 = 0;
    var members = module_scope.members.valueIterator();
    while (members.next()) |member| {
        symbols[member.ref.innerIndex()].nested_scope_slot = valid_slot;
    }
    for (module_scope.generated.slice()) |ref| {
        symbols[ref.innerIndex()].nested_scope_slot = valid_slot;
    }

    for (module_scope.children.slice()) |child| {
        slot_counts.unionMax(assignNestedScopeSlotsHelper(&sorted_members, child, symbols, js_ast.SlotCounts{}));
    }

    // Then set the nested scope slots of top-level symbols back to zero. Top-
    // level symbols are not supposed to have nested scope slots.
    members = module_scope.members.valueIterator();

    while (members.next()) |member| {
        symbols[member.ref.innerIndex()].nested_scope_slot = js_ast.Symbol.invalid_nested_scope_slot;
    }
    for (module_scope.generated.slice()) |ref| {
        symbols[ref.innerIndex()].nested_scope_slot = js_ast.Symbol.invalid_nested_scope_slot;
    }

    return slot_counts;
}

pub fn assignNestedScopeSlotsHelper(sorted_members: *std.ArrayList(u32), scope: *js_ast.Scope, symbols: []js_ast.Symbol, slot_to_copy: js_ast.SlotCounts) js_ast.SlotCounts {
    var slot = slot_to_copy;
    // Sort member map keys for determinism
    {
        sorted_members.clearRetainingCapacity();
        sorted_members.ensureUnusedCapacity(scope.members.count()) catch unreachable;
        sorted_members.items.len = scope.members.count();
        var sorted_members_buf = sorted_members.items;
        var members = scope.members.valueIterator();
        var i: usize = 0;
        while (members.next()) |member| {
            sorted_members_buf[i] = member.ref.innerIndex();
            i += 1;
        }
        std.sort.pdq(u32, sorted_members_buf, {}, std.sort.asc(u32));

        // Assign slots for this scope's symbols. Only do this if the slot is
        // not already assigned. Nested scopes have copies of symbols from parent
        // scopes and we want to use the slot from the parent scope, not child scopes.
        for (sorted_members_buf) |inner_index| {
            var symbol = &symbols[inner_index];
            const ns = symbol.slotNamespace();
            if (ns != .must_not_be_renamed and symbol.nestedScopeSlot() == null) {
                symbol.nested_scope_slot = slot.slots.get(ns);
                slot.slots.getPtr(ns).* += 1;
            }
        }
    }

    for (scope.generated.slice()) |ref| {
        var symbol = &symbols[ref.innerIndex()];
        const ns = symbol.slotNamespace();
        if (ns != .must_not_be_renamed and symbol.nestedScopeSlot() == null) {
            symbol.nested_scope_slot = slot.slots.get(ns);
            slot.slots.getPtr(ns).* += 1;
        }
    }

    // Labels are always declared in a nested scope, so we don't need to check.
    if (scope.label_ref) |ref| {
        var symbol = &symbols[ref.innerIndex()];
        const ns = js_ast.Symbol.SlotNamespace.label;
        symbol.nested_scope_slot = slot.slots.get(ns);
        slot.slots.getPtr(ns).* += 1;
    }

    // Assign slots for the symbols of child scopes
    var slot_counts = slot;
    for (scope.children.slice()) |child| {
        slot_counts.unionMax(assignNestedScopeSlotsHelper(sorted_members, child, symbols, slot));
    }

    return slot_counts;
}

pub const StableSymbolCount = struct {
    stable_source_index: u32,
    ref: Ref,
    count: u32,

    pub const Array = std.ArrayList(StableSymbolCount);

    pub fn lessThan(_: void, i: StableSymbolCount, j: StableSymbolCount) bool {
        if (i.count > j.count) return true;
        if (i.count < j.count) return false;
        if (i.stable_source_index < j.stable_source_index) return true;
        if (i.stable_source_index > j.stable_source_index) return false;

        return i.ref.innerIndex() < j.ref.innerIndex();
    }
};

const SlotAndCount = packed struct {
    slot: u32,
    count: u32,

    pub const Array = std.ArrayList(SlotAndCount);

    pub fn lessThan(_: void, a: SlotAndCount, b: SlotAndCount) bool {
        return a.count > b.count or (a.count == b.count and a.slot < b.slot);
    }
};

pub const NumberRenamer = struct {
    symbols: js_ast.Symbol.Map,
    names: []bun.BabyList(string) = &.{},
    allocator: std.mem.Allocator,
    temp_allocator: std.mem.Allocator,
    number_scope_pool: bun.HiveArray(NumberScope, 128).Fallback,
    arena: bun.ArenaAllocator,
    root: NumberScope = .{},
    name_stack_fallback: std.heap.StackFallbackAllocator(512) = undefined,
    name_temp_allocator: std.mem.Allocator = undefined,

    pub fn deinit(self: *NumberRenamer) void {
        self.allocator.free(self.names);
        self.root.deinit(self.temp_allocator);
        self.arena.deinit();
    }

    pub fn toRenamer(this: *NumberRenamer) Renamer {
        return .{
            .NumberRenamer = this,
        };
    }

    pub fn originalName(r: *NumberRenamer, ref: Ref) string {
        if (ref.isSourceContentsSlice()) {
            unreachable;
        }

        const resolved = r.symbols.follow(ref);
        return r.symbols.getConst(resolved).?.original_name;
    }

    pub fn assignName(r: *NumberRenamer, scope: *NumberScope, input_ref: Ref) void {
        const ref = r.symbols.follow(input_ref);

        // Don't rename the same symbol more than once
        var inner: *bun.BabyList(string) = &r.names[ref.sourceIndex()];
        if (inner.len > ref.innerIndex() and inner.at(ref.innerIndex()).len > 0) return;

        // Don't rename unbound symbols, symbols marked as reserved names, labels, or private names
        const symbol = r.symbols.get(ref).?;
        if (symbol.slotNamespace() != .default) {
            return;
        }

        r.name_stack_fallback.fixed_buffer_allocator.end_index = 0;
        const name = switch (scope.findUnusedName(r.allocator, r.name_temp_allocator, symbol.original_name)) {
            .renamed => |name| name,
            .no_collision => symbol.original_name,
        };
        const new_len = @max(inner.len, ref.innerIndex() + 1);
        if (inner.cap <= new_len) {
            const prev_cap = inner.len;
            inner.ensureUnusedCapacity(r.allocator, new_len - prev_cap) catch unreachable;
            const to_write = inner.ptr[prev_cap..inner.cap];
            @memset(std.mem.sliceAsBytes(to_write), 0);
        }
        inner.len = new_len;
        inner.mut(ref.innerIndex()).* = name;
    }

    pub fn init(
        allocator: std.mem.Allocator,
        temp_allocator: std.mem.Allocator,
        symbols: js_ast.Symbol.Map,
        root_names: bun.StringHashMapUnmanaged(u32),
    ) !*NumberRenamer {
        var renamer = try allocator.create(NumberRenamer);
        renamer.* = NumberRenamer{
            .symbols = symbols,
            .allocator = allocator,
            .temp_allocator = temp_allocator,
            .names = try allocator.alloc(bun.BabyList(string), symbols.symbols_for_source.len),
            .number_scope_pool = undefined,
            .arena = bun.ArenaAllocator.init(temp_allocator),
        };
        renamer.name_stack_fallback = .{
            .buffer = undefined,
            .fallback_allocator = renamer.arena.allocator(),
            .fixed_buffer_allocator = undefined,
        };
        renamer.name_temp_allocator = renamer.name_stack_fallback.get();
        renamer.number_scope_pool = bun.HiveArray(NumberScope, 128).Fallback.init(renamer.arena.allocator());
        renamer.root.name_counts = root_names;
        if (comptime Environment.allow_assert and !Environment.isWindows) {
            if (std.os.getenv("BUN_DUMP_SYMBOLS") != null)
                symbols.dump();
        }

        @memset(std.mem.sliceAsBytes(renamer.names), 0);

        return renamer;
    }

    pub fn assignNamesRecursive(r: *NumberRenamer, scope: *js_ast.Scope, source_index: u32, parent: ?*NumberScope, sorted: *std.ArrayList(u32)) void {
        var s = r.number_scope_pool.get();
        s.* = NumberScope{
            .parent = parent,
            .name_counts = .{},
        };
        defer {
            s.deinit(r.temp_allocator);
            r.number_scope_pool.put(s);
        }

        assignNamesRecursiveWithNumberScope(r, s, scope, source_index, sorted);
    }

    fn assignNamesInScope(
        r: *NumberRenamer,
        s: *NumberScope,
        scope: *js_ast.Scope,
        source_index: u32,
        sorted: *std.ArrayList(u32),
    ) void {
        {
            sorted.clearRetainingCapacity();
            sorted.ensureUnusedCapacity(scope.members.count()) catch unreachable;
            sorted.items.len = scope.members.count();
            var remaining = sorted.items;
            var value_iter = scope.members.valueIterator();
            while (value_iter.next()) |value_ref| {
                if (comptime Environment.allow_assert)
                    bun.assert(!value_ref.ref.isSourceContentsSlice());

                remaining[0] = value_ref.ref.innerIndex();
                remaining = remaining[1..];
            }
            bun.assert(remaining.len == 0);
            std.sort.pdq(u32, sorted.items, {}, std.sort.asc(u32));

            for (sorted.items) |inner_index| {
                r.assignName(s, Ref.init(@as(Ref.Int, @intCast(inner_index)), source_index, false));
            }
        }

        for (scope.generated.slice()) |ref| {
            r.assignName(s, ref);
        }
    }

    pub fn assignNamesRecursiveWithNumberScope(r: *NumberRenamer, initial_scope: *NumberScope, scope_: *js_ast.Scope, source_index: u32, sorted: *std.ArrayList(u32)) void {
        var s = initial_scope;
        var scope = scope_;
        defer if (s != initial_scope) {
            s.deinit(r.temp_allocator);
            r.number_scope_pool.put(s);
        };

        // Ignore function argument scopes
        if (scope.kind == .function_args and scope.children.len == 1) {
            scope = scope.children.ptr[0];
            bun.assert(scope.kind == .function_body);
        }

        while (true) {
            if (scope.members.count() > 0 or scope.generated.len > 0) {
                const new_child_scope = r.number_scope_pool.get();
                new_child_scope.* = .{
                    .parent = s,
                    .name_counts = .{},
                };
                s = new_child_scope;

                r.assignNamesInScope(s, scope, source_index, sorted);
            }

            if (scope.children.len == 1) {
                scope = scope.children.ptr[0];
                if (scope.kind == .function_args and scope.children.len == 1) {
                    scope = scope.children.ptr[0];
                    bun.assert(scope.kind == .function_body);
                }
            } else {
                break;
            }
        }

        // Symbols in child scopes may also have to be renamed to avoid conflicts
        for (scope.children.slice()) |child| {
            r.assignNamesRecursiveWithNumberScope(s, child, source_index, sorted);
        }
    }

    pub fn addTopLevelSymbol(r: *NumberRenamer, ref: Ref) void {
        r.assignName(&r.root, ref);
    }

    pub fn addTopLevelDeclaredSymbols(r: *NumberRenamer, declared_symbols: js_ast.DeclaredSymbol.List) void {
        var decls = declared_symbols;
        js_ast.DeclaredSymbol.forEachTopLevelSymbol(&decls, r, addTopLevelSymbol);
    }

    pub fn nameForSymbol(renamer: *NumberRenamer, ref: Ref) string {
        if (ref.isSourceContentsSlice()) {
            bun.unreachablePanic("Unexpected unbound symbol!\n{any}", .{ref});
        }

        const resolved = renamer.symbols.follow(ref);

        const source_index = resolved.sourceIndex();
        const inner_index = resolved.innerIndex();

        const renamed_list = renamer.names[source_index];

        if (renamed_list.len > inner_index) {
            const renamed = renamed_list.at(inner_index).*;
            if (renamed.len > 0) {
                return renamed;
            }
        }

        return renamer.symbols.symbols_for_source.at(source_index).at(inner_index).original_name;
    }

    pub const NumberScope = struct {
        parent: ?*NumberScope = null,
        name_counts: bun.StringHashMapUnmanaged(u32) = .{},

        pub fn deinit(this: *NumberScope, allocator: std.mem.Allocator) void {
            this.name_counts.deinit(allocator);
            this.* = undefined;
        }

        pub const NameUse = union(enum) {
            unused: void,
            same_scope: u32,
            used: void,

            pub fn find(this: *NumberScope, name: []const u8) NameUse {
                // This version doesn't allocate
                if (comptime Environment.allow_assert)
                    bun.assert(JSLexer.isIdentifier(name));

                // avoid rehashing the same string over for each scope
                const ctx = bun.StringHashMapContext.pre(name);

                if (this.name_counts.getAdapted(name, ctx)) |count| {
                    return .{ .same_scope = count };
                }

                var s: ?*NumberScope = this.parent;

                while (s) |scope| : (s = scope.parent) {
                    if (scope.name_counts.containsAdapted(name, ctx)) {
                        return .{ .used = {} };
                    }
                }

                return .{ .unused = {} };
            }
        };

        const UnusedName = union(enum) {
            no_collision: void,
            renamed: string,
        };

        /// Caller must use an arena allocator
        pub fn findUnusedName(this: *NumberScope, allocator: std.mem.Allocator, temp_allocator: std.mem.Allocator, input_name: []const u8) UnusedName {
            var name = bun.MutableString.ensureValidIdentifier(input_name, temp_allocator) catch unreachable;

            switch (NameUse.find(this, name)) {
                .unused => {},
                else => |use| {
                    var tries: u32 = if (use == .used)
                        1
                    else
                        // To avoid O(n^2) behavior, the number must start off being the number
                        // that we used last time there was a collision with this name. Otherwise
                        // if there are many collisions with the same name, each name collision
                        // would have to increment the counter past all previous name collisions
                        // which is a O(n^2) time algorithm. Only do this if this symbol comes
                        // from the same scope as the previous one since sibling scopes can reuse
                        // the same name without problems.
                        use.same_scope;

                    const prefix = name;

                    tries += 1;

                    var mutable_name = MutableString.initEmpty(temp_allocator);
                    mutable_name.growIfNeeded(prefix.len + 4) catch unreachable;
                    mutable_name.appendSlice(prefix) catch unreachable;
                    mutable_name.appendInt(tries) catch unreachable;

                    switch (NameUse.find(this, mutable_name.toOwnedSliceLeaky())) {
                        .unused => {
                            name = mutable_name.toOwnedSliceLeaky();

                            if (use == .same_scope) {
                                const existing = this.name_counts.getOrPut(allocator, prefix) catch unreachable;
                                if (!existing.found_existing) {
                                    if (strings.eqlLong(input_name, prefix, true)) {
                                        existing.key_ptr.* = input_name;
                                    } else {
                                        existing.key_ptr.* = allocator.dupe(u8, prefix) catch unreachable;
                                    }
                                }

                                existing.value_ptr.* = tries;
                            }
                        },
                        else => |cur_use| {
                            while (true) {
                                mutable_name.resetTo(prefix.len);
                                mutable_name.appendInt(tries) catch unreachable;

                                tries += 1;

                                switch (NameUse.find(this, mutable_name.toOwnedSliceLeaky())) {
                                    .unused => {
                                        if (cur_use == .same_scope) {
                                            const existing = this.name_counts.getOrPut(allocator, prefix) catch unreachable;
                                            if (!existing.found_existing) {
                                                if (strings.eqlLong(input_name, prefix, true)) {
                                                    existing.key_ptr.* = input_name;
                                                } else {
                                                    existing.key_ptr.* = allocator.dupe(u8, prefix) catch unreachable;
                                                }
                                            }

                                            existing.value_ptr.* = tries;
                                        }

                                        name = mutable_name.toOwnedSliceLeaky();
                                        break;
                                    },
                                    else => {},
                                }
                            }
                        },
                    }
                },
            }

            // Each name starts off with a count of 1 so that the first collision with
            // "name" is called "name2"
            if (strings.eqlLong(name, input_name, true)) {
                this.name_counts.putNoClobber(allocator, input_name, 1) catch unreachable;
                return .{ .no_collision = {} };
            }

            name = allocator.dupe(u8, name) catch unreachable;

            this.name_counts.putNoClobber(allocator, name, 1) catch unreachable;
            return .{ .renamed = name };
        }
    };
};

pub const ExportRenamer = struct {
    string_buffer: bun.MutableString,
    used: bun.StringHashMap(u32),
    count: isize = 0,

    pub fn init(allocator: std.mem.Allocator) ExportRenamer {
        return ExportRenamer{
            .string_buffer = MutableString.initEmpty(allocator),
            .used = bun.StringHashMap(u32).init(allocator),
        };
    }

    pub fn clearRetainingCapacity(this: *ExportRenamer) void {
        this.used.clearRetainingCapacity();
        this.string_buffer.reset();
    }

    pub fn deinit(this: *ExportRenamer) void {
        this.used.deinit();
        this.string_buffer.deinit();
    }

    pub fn nextRenamedName(this: *ExportRenamer, input: []const u8) string {
        var entry = this.used.getOrPut(input) catch unreachable;
        var tries: u32 = 1;
        if (entry.found_existing) {
            while (true) {
                this.string_buffer.reset();
                var writer = this.string_buffer.writer();
                writer.print("{s}{d}", .{ input, tries }) catch unreachable;
                tries += 1;
                const attempt = this.string_buffer.toOwnedSliceLeaky();
                entry = this.used.getOrPut(attempt) catch unreachable;
                if (!entry.found_existing) {
                    const to_use = this.string_buffer.allocator.dupe(u8, attempt) catch unreachable;
                    entry.key_ptr.* = to_use;
                    entry.value_ptr.* = tries;

                    entry = this.used.getOrPut(input) catch unreachable;
                    entry.value_ptr.* = tries;
                    return to_use;
                }
            }
        } else {
            entry.value_ptr.* = tries;
        }

        return entry.key_ptr.*;
    }

    pub fn nextMinifiedName(this: *ExportRenamer, allocator: std.mem.Allocator) !string {
        const name = try js_ast.NameMinifier.defaultNumberToMinifiedName(allocator, this.count);
        this.count += 1;
        return name;
    }
};

pub fn computeInitialReservedNames(
    allocator: std.mem.Allocator,
) !bun.StringHashMapUnmanaged(u32) {
    if (comptime bun.Environment.isWasm) {
        unreachable;
    }

    var names = bun.StringHashMapUnmanaged(u32){};

    const extras = .{
        "Promise",
        "Require",
    };

    try names.ensureTotalCapacityContext(
        allocator,
        @as(u32, @truncate(JSLexer.Keywords.keys().len + JSLexer.StrictModeReservedWords.keys().len + 1 + extras.len)),
        bun.StringHashMapContext{},
    );

    for (JSLexer.Keywords.keys()) |keyword| {
        names.putAssumeCapacity(keyword, 1);
    }

    for (JSLexer.StrictModeReservedWords.keys()) |keyword| {
        names.putAssumeCapacity(keyword, 1);
    }

    inline for (comptime extras) |extra| {
        names.putAssumeCapacity(extra, 1);
    }

    return names;
}

pub fn computeReservedNamesForScope(
    scope: *js_ast.Scope,
    symbols: *const js_ast.Symbol.Map,
    names_: *bun.StringHashMapUnmanaged(u32),
    allocator: std.mem.Allocator,
) void {
    var names = names_.*;
    defer names_.* = names;

    var member_iter = scope.members.valueIterator();
    while (member_iter.next()) |member| {
        const symbol = symbols.get(member.ref).?;
        if (symbol.kind == .unbound or symbol.must_not_be_renamed) {
            names.put(allocator, symbol.original_name, 1) catch unreachable;
        }
    }

    for (scope.generated.slice()) |ref| {
        const symbol = symbols.get(ref).?;
        if (symbol.kind == .unbound or symbol.must_not_be_renamed) {
            names.put(allocator, symbol.original_name, 1) catch unreachable;
        }
    }

    // If there's a direct "eval" somewhere inside the current scope, continue
    // traversing down the scope tree until we find it to get all reserved names
    if (scope.contains_direct_eval) {
        for (scope.children.slice()) |child| {
            if (child.contains_direct_eval) {
                names_.* = names;
                computeReservedNamesForScope(child, symbols, &names, allocator);
            }
        }
    }
}