map_ordered_iter.go

package g

import (
	"context"
	"iter"

	"github.com/enetx/g/cmp"
)

// Pull converts the “push-style” iterator sequence seq
// into a “pull-style” iterator accessed by the two functions
// next and stop.
//
// Next returns the next pair in the sequence
// and a boolean indicating whether the pair is valid.
// When the sequence is over, next returns a pair of zero values and false.
// It is valid to call next after reaching the end of the sequence
// or after calling stop. These calls will continue
// to return a pair of zero values and false.
//
// Stop ends the iteration. It must be called when the caller is
// no longer interested in next values and next has not yet
// signaled that the sequence is over (with a false boolean return).
// It is valid to call stop multiple times and when next has
// already returned false.
//
// It is an error to call next or stop from multiple goroutines
// simultaneously.
func (seq SeqMapOrd[K, V]) Pull() (func() (K, V, bool), func()) {
	return iter.Pull2(iter.Seq2[K, V](seq))
}

// Keys returns an iterator containing all the keys in the ordered Map.
func (seq SeqMapOrd[K, V]) Keys() SeqSlice[K] { return keysMapOrd(seq) }

// Values returns an iterator containing all the values in the ordered Map.
func (seq SeqMapOrd[K, V]) Values() SeqSlice[V] { return valuesMapOrd(seq) }

// Unzip returns a tuple of slices containing keys and values from the ordered map.
func (seq SeqMapOrd[K, V]) Unzip() (SeqSlice[K], SeqSlice[V]) { return seq.Keys(), seq.Values() }

// SortBy applies a custom sorting function to the elements in the iterator
// and returns a new iterator containing the sorted elements.
//
// The sorting function 'fn' should take two arguments, 'a' and 'b', of type Pair[K, V],
// and return true if 'a' should be ordered before 'b', and false otherwise.
//
// Example:
//
//	m := g.NewMapOrd[g.Int, g.String]()
//	m.
//		Set(6, "bb").
//		Set(0, "dd").
//		Set(1, "aa").
//		Set(5, "xx").
//		Set(2, "cc").
//		Set(3, "ff").
//		Set(4, "zz").
//		Iter().
//		SortBy(
//			func(a, b g.Pair[g.Int, g.String]) cmp.Ordering {
//				return a.Key.Cmp(b.Key)
//				// return a.Value.Cmp(b.Value)
//			}).
//		Collect().
//		Print()
//
// Output: MapOrd{0:dd, 1:aa, 2:cc, 3:ff, 4:zz, 5:xx, 6:bb}
//
// The returned iterator is of type SeqMapOrd[K, V], which implements the iterator
// interface for further iteration over the sorted elements.
func (seq SeqMapOrd[K, V]) SortBy(fn func(a, b Pair[K, V]) cmp.Ordering) SeqMapOrd[K, V] {
	return sortByMapOrd(seq, fn)
}

// SortByKey applies a custom sorting function to the keys in the iterator
// and returns a new iterator containing the sorted elements.
//
// The sorting function 'fn' should take two arguments, 'a' and 'b', of type K,
// and return true if 'a' should be ordered before 'b', and false otherwise.
//
// Example:
//
//	m := g.NewMapOrd[g.Int, g.String]()
//	m.
//		Set(6, "bb").
//		Set(0, "dd").
//		Set(1, "aa").
//		Set(5, "xx").
//		Set(2, "cc").
//		Set(3, "ff").
//		Set(4, "zz").
//		Iter().
//		SortByKey(g.Int.Cmp).
//		Collect().
//		Print()
//
// Output: MapOrd{0:dd, 1:aa, 2:cc, 3:ff, 4:zz, 5:xx, 6:bb}
func (seq SeqMapOrd[K, V]) SortByKey(fn func(a, b K) cmp.Ordering) SeqMapOrd[K, V] {
	return sortByKeyMapOrd(seq, fn)
}

// SortByValue applies a custom sorting function to the values in the iterator
// and returns a new iterator containing the sorted elements.
//
// The sorting function 'fn' should take two arguments, 'a' and 'b', of type V,
// and return true if 'a' should be ordered before 'b', and false otherwise.
//
// Example:
//
//	m := g.NewMapOrd[g.Int, g.String]()
//	m.
//		Set(6, "bb").
//		Set(0, "dd").
//		Set(1, "aa").
//		Set(5, "xx").
//		Set(2, "cc").
//		Set(3, "ff").
//		Set(4, "zz").
//		Iter().
//		SortByValue(g.String.Cmp).
//		Collect().
//		Print()
//
// Output: MapOrd{1:aa, 6:bb, 2:cc, 0:dd, 3:ff, 5:xx, 4:zz}
func (seq SeqMapOrd[K, V]) SortByValue(fn func(a, b V) cmp.Ordering) SeqMapOrd[K, V] {
	return sortByValueMapOrd(seq, fn)
}

// Inspect creates a new iterator that wraps around the current iterator
// and allows inspecting each key-value pair as it passes through.
func (seq SeqMapOrd[K, V]) Inspect(fn func(k K, v V)) SeqMapOrd[K, V] { return inspectMapOrd(seq, fn) }

// StepBy creates a new iterator that iterates over every N-th element of the original iterator.
// This function is useful when you want to skip a specific number of elements between each iteration.
//
// Parameters:
// - n int: The step size, indicating how many elements to skip between each iteration.
//
// Returns:
// - SeqMapOrd[K, V]: A new iterator that produces key-value pairs from the original iterator with a step size of N.
//
// Example usage:
//
//	mapIter := g.MapOrd[string, int]{{"one", 1}, {"two", 2}, {"three", 3}}.Iter()
//	iter := mapIter.StepBy(2)
//	result := iter.Collect()
//	result.Print()
//
// Output: MapOrd{one:1, three:3}
//
// The resulting iterator will produce key-value pairs from the original iterator with a step size of N.
func (seq SeqMapOrd[K, V]) StepBy(n uint) SeqMapOrd[K, V] { return stepbyMapOrd(seq, n) }

// Chain concatenates the current iterator with other iterators, returning a new iterator.
//
// The function creates a new iterator that combines the elements of the current iterator
// with elements from the provided iterators in the order they are given.
//
// Params:
//
// - seqs ([]seqMapOrd[K, V]): Other iterators to be concatenated with the current iterator.
//
// Returns:
//
// - SeqMapOrd[K, V]: A new iterator containing elements from the current iterator and the provided iterators.
//
// Example usage:
//
//	iter1 := g.NewMapOrd[int, string]()
//	iter1.Set(1, "a").Iter()
//
//	iter2 := g.NewMapOrd[int, string]()
//	iter2.Set(2, "b").Iter()
//
//	// Concatenating iterators and collecting the result.
//	iter1.Chain(iter2).Collect().Print()
//
// Output: MapOrd{1:a, 2:b}
//
// The resulting iterator will contain elements from both iterators in the specified order.
func (seq SeqMapOrd[K, V]) Chain(seqs ...SeqMapOrd[K, V]) SeqMapOrd[K, V] {
	return chainMapOrd(append([]SeqMapOrd[K, V]{seq}, seqs...)...)
}

// Count consumes the iterator, counting the number of iterations and returning it.
func (seq SeqMapOrd[K, V]) Count() Int { return countMapOrd(seq) }

// Collect collects all key-value pairs from the iterator and returns a MapOrd.
func (seq SeqMapOrd[K, V]) Collect() MapOrd[K, V] {
	collection := NewMapOrd[K, V]()

	seq(func(k K, v V) bool {
		collection.Set(k, v)
		return true
	})

	return collection
}

// Skip returns a new iterator skipping the first n elements.
//
// The function creates a new iterator that skips the first n elements of the current iterator
// and returns an iterator starting from the (n+1)th element.
//
// Params:
//
// - n (uint): The number of elements to skip from the beginning of the iterator.
//
// Returns:
//
// - SeqMapOrd[K, V]: An iterator that starts after skipping the first n elements.
//
// Example usage:
//

//	iter := g.NewMapOrd[int, string]()
//	iter.
//		Set(1, "a").
//		Set(2, "b").
//		Set(3, "c").
//		Set(4, "d").
//		Iter()
//
//	// Skipping the first two elements and collecting the rest.
//	iter.Skip(2).Collect().Print()
//
// Output: MapOrd{3:c, 4:d}
//
// The resulting iterator will start after skipping the specified number of elements.
func (seq SeqMapOrd[K, V]) Skip(n uint) SeqMapOrd[K, V] { return skipMapOrd(seq, n) }

// Exclude returns a new iterator excluding elements that satisfy the provided function.
//
// The function creates a new iterator excluding elements from the current iterator
// for which the provided function returns true.
//
// Params:
//
// - fn (func(K, V) bool): The function used to determine exclusion criteria for elements.
//
// Returns:
//
// - SeqMapOrd[K, V]: A new iterator excluding elements that satisfy the given condition.
//
// Example usage:
//
//	mo := g.NewMapOrd[int, int]()
//	mo.
//		Set(1, 1).
//		Set(2, 2).
//		Set(3, 3).
//		Set(4, 4).
//		Set(5, 5)
//
//	notEven := mo.Iter().
//		Exclude(
//			func(k, v int) bool {
//				return v%2 == 0
//			}).
//		Collect()
//	notEven.Print()
//
// Output: MapOrd{1:1, 3:3, 5:5}
//
// The resulting iterator will exclude elements based on the provided condition.
func (seq SeqMapOrd[K, V]) Exclude(fn func(K, V) bool) SeqMapOrd[K, V] { return excludeMapOrd(seq, fn) }

// Filter returns a new iterator containing only the elements that satisfy the provided function.
//
// The function creates a new iterator including elements from the current iterator
// for which the provided function returns true.
//
// Params:
//
// - fn (func(K, V) bool): The function used to determine inclusion criteria for elements.
//
// Returns:
//
// - SeqMapOrd[K, V]: A new iterator containing elements that satisfy the given condition.
//
// Example usage:
//
//	mo := g.NewMapOrd[int, int]()
//	mo.
//		Set(1, 1).
//		Set(2, 2).
//		Set(3, 3).
//		Set(4, 4).
//		Set(5, 5)
//
//	even := mo.Iter().
//		Filter(
//			func(k, v int) bool {
//				return v%2 == 0
//			}).
//		Collect()
//	even.Print()
//
// Output: MapOrd{2:2, 4:4}
//
// The resulting iterator will include elements based on the provided condition.
func (seq SeqMapOrd[K, V]) Filter(fn func(K, V) bool) SeqMapOrd[K, V] { return filterMapOrd(seq, fn) }

// The resulting Option may contain the first element that satisfies the condition, or None if not found.
func (seq SeqMapOrd[K, V]) Find(fn func(k K, v V) bool) Option[Pair[K, V]] {
	return findMapOrd(seq, fn)
}

// ForEach iterates through all elements and applies the given function to each key-value pair.
//
// The function applies the provided function to each key-value pair in the iterator.
//
// Params:
//
// - fn (func(K, V)): The function to be applied to each key-value pair in the iterator.
//
// Example usage:
//
//	iter := g.NewMapOrd[int, int]()
//	iter.
//		Set(1, 1).
//		Set(2, 2).
//		Set(3, 3).
//		Set(4, 4).
//		Set(5, 5).
//		Iter()
//
//	iter.ForEach(func(key K, val V) {
//	    // Process key-value pair
//	})
//
// The provided function will be applied to each key-value pair in the iterator.
func (seq SeqMapOrd[K, V]) ForEach(fn func(k K, v V)) {
	seq(func(k K, v V) bool {
		fn(k, v)
		return true
	})
}

// Map creates a new iterator by applying the given function to each key-value pair.
//
// The function creates a new iterator by applying the provided function to each key-value pair in the iterator.
//
// Params:
//
// - fn (func(K, V) (K, V)): The function used to transform each key-value pair in the iterator.
//
// Returns:
//
// - SeqMapOrd[K, V]: A new iterator containing transformed key-value pairs.
//
// Example usage:
//
//	mo := g.NewMapOrd[int, int]()
//	mo.
//		Set(1, 1).
//		Set(2, 2).
//		Set(3, 3).
//		Set(4, 4).
//		Set(5, 5)
//
//	momap := mo.Iter().
//		Map(
//			func(k, v int) (int, int) {
//				return k * k, v * v
//			}).
//		Collect()
//
//	momap.Print()
//
// Output: MapOrd{1:1, 4:4, 9:9, 16:16, 25:25}
//
// The resulting iterator will contain transformed key-value pairs.
func (seq SeqMapOrd[K, V]) Map(transform func(K, V) (K, V)) SeqMapOrd[K, V] {
	return mapiMapOrd(seq, transform)
}

// Range iterates through elements until the given function returns false.
//
// The function iterates through the key-value pairs in the iterator, applying the provided function to each pair.
// It continues iterating until the function returns false.
//
// Params:
//
// - fn (func(K, V) bool): The function to be applied to each key-value pair in the iterator.
//
// Example usage:
//
//	iter := g.NewMapOrd[int, int]()
//	iter.
//		Set(1, 1).
//		Set(2, 2).
//		Set(3, 3).
//		Set(4, 4).
//		Set(5, 5).
//		Iter()
//
//	iter.Range(func(k, v int) bool {
//	    fmt.Println(v) // Replace this with the function logic you need.
//	    return v < 5 // Replace this with the condition for continuing iteration.
//	})
//
// The iteration will stop when the provided function returns false.
func (seq SeqMapOrd[K, V]) Range(fn func(k K, v V) bool) {
	seq(func(k K, v V) bool {
		return fn(k, v)
	})
}

// Take returns a new iterator with the first n elements.
// The function creates a new iterator containing the first n elements from the original iterator.
func (seq SeqMapOrd[K, V]) Take(limit uint) SeqMapOrd[K, V] { return takeMapOrd(seq, limit) }

// ToChan converts the iterator into a channel, optionally with context(s).
//
// The function converts the key-value pairs from the iterator into a channel, allowing iterative processing
// using channels. It can be used to stream key-value pairs for concurrent or asynchronous operations.
//
// Params:
//
// - ctxs (...context.Context): Optional context(s) that can be used to cancel or set deadlines for the operation.
//
// Returns:
//
// - chan Pair[K, V]: A channel emitting key-value pairs from the iterator.
//
// Example usage:
//
//	iter := g.NewMapOrd[int, int]()
//	iter.
//		Set(1, 1).
//		Set(2, 2).
//		Set(3, 3).
//		Set(4, 4).
//		Set(5, 5).
//		Iter()
//
//	ctx, cancel := context.WithCancel(context.Background())
//	defer cancel() // Ensure cancellation to avoid goroutine leaks.
//
//	ch := iter.ToChan(ctx)
//	for pair := range ch {
//	    // Process key-value pair from the channel
//	}
//
// The function converts the iterator into a channel to allow sequential or concurrent processing of key-value pairs.
func (seq SeqMapOrd[K, V]) ToChan(ctxs ...context.Context) chan Pair[K, V] {
	ch := make(chan Pair[K, V])

	ctx := context.Background()
	if len(ctxs) != 0 {
		ctx = ctxs[0]
	}

	go func() {
		defer close(ch)

		for k, v := range seq {
			select {
			case <-ctx.Done():
				return
			default:
				ch <- Pair[K, V]{k, v}
			}
		}
	}()

	return ch
}

func ToSeqMapOrd[K, V any](mo MapOrd[K, V]) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		for _, v := range mo {
			if !yield(v.Key, v.Value) {
				return
			}
		}
	}
}

func sortByMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(a, b Pair[K, V]) cmp.Ordering) SeqMapOrd[K, V] {
	items := seq.Collect()
	items.SortBy(fn)

	return items.Iter()
}

func sortByKeyMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(a, b K) cmp.Ordering) SeqMapOrd[K, V] {
	items := seq.Collect()
	items.SortByKey(fn)

	return items.Iter()
}

func sortByValueMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(a, b V) cmp.Ordering) SeqMapOrd[K, V] {
	items := seq.Collect()
	items.SortByValue(fn)

	return items.Iter()
}

func inspectMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(K, V)) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		seq(func(k K, v V) bool {
			fn(k, v)
			return yield(k, v)
		})
	}
}

func stepbyMapOrd[K, V any](seq SeqMapOrd[K, V], n uint) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		i := uint(0)
		seq(func(k K, v V) bool {
			i++
			if (i-1)%n == 0 {
				return yield(k, v)
			}

			return true
		})
	}
}

func chainMapOrd[K, V any](seqs ...SeqMapOrd[K, V]) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		for _, seq := range seqs {
			seq(func(k K, v V) bool {
				return yield(k, v)
			})
		}
	}
}

func skipMapOrd[K, V any](seq SeqMapOrd[K, V], n uint) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		seq(func(k K, v V) bool {
			if n > 0 {
				n--
				return true
			}
			return yield(k, v)
		})
	}
}

func mapiMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(K, V) (K, V)) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		seq(func(k K, v V) bool {
			return yield(fn(k, v))
		})
	}
}

func filterMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(K, V) bool) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		seq(func(k K, v V) bool {
			if fn(k, v) {
				return yield(k, v)
			}
			return true
		})
	}
}

func excludeMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(K, V) bool) SeqMapOrd[K, V] {
	return filterMapOrd(seq, func(k K, v V) bool { return !fn(k, v) })
}

func takeMapOrd[K, V any](seq SeqMapOrd[K, V], n uint) SeqMapOrd[K, V] {
	return func(yield func(K, V) bool) {
		seq(func(k K, v V) bool {
			if n == 0 {
				return false
			}
			n--
			return yield(k, v)
		})
	}
}

func keysMapOrd[K, V any](seq SeqMapOrd[K, V]) SeqSlice[K] {
	return func(yield func(K) bool) {
		seq(func(k K, _ V) bool {
			return yield(k)
		})
	}
}

func valuesMapOrd[K, V any](seq SeqMapOrd[K, V]) SeqSlice[V] {
	return func(yield func(V) bool) {
		seq(func(_ K, v V) bool {
			return yield(v)
		})
	}
}

func findMapOrd[K, V any](seq SeqMapOrd[K, V], fn func(K, V) bool) (r Option[Pair[K, V]]) {
	seq(func(k K, v V) bool {
		if !fn(k, v) {
			return true
		}
		r = Some(Pair[K, V]{k, v})
		return false
	})

	return r
}

func countMapOrd[K, V any](seq SeqMapOrd[K, V]) Int {
	var counter Int
	seq(func(K, V) bool {
		counter++
		return true
	})

	return counter
}