__init__.py

from contextlib import contextmanager
from collections import OrderedDict
import base64
import click
import hashlib
import json
import mergedeep
import os
import re
import shlex
import tempfile
import time
import types
import shutil
import urllib
import numbers
import yaml

try:
    import pysqlite3 as sqlite3
except ImportError:
    import sqlite3

# From https://www.sqlite.org/lang_keywords.html
reserved_words = set(
    (
        "abort action add after all alter analyze and as asc attach autoincrement "
        "before begin between by cascade case cast check collate column commit "
        "conflict constraint create cross current_date current_time "
        "current_timestamp database default deferrable deferred delete desc detach "
        "distinct drop each else end escape except exclusive exists explain fail "
        "for foreign from full glob group having if ignore immediate in index "
        "indexed initially inner insert instead intersect into is isnull join key "
        "left like limit match natural no not notnull null of offset on or order "
        "outer plan pragma primary query raise recursive references regexp reindex "
        "release rename replace restrict right rollback row savepoint select set "
        "table temp temporary then to transaction trigger union unique update using "
        "vacuum values view virtual when where with without"
    ).split()
)

SPATIALITE_DOCKERFILE_EXTRAS = r"""
RUN apt-get update && \
    apt-get install -y python3-dev gcc libsqlite3-mod-spatialite && \
    rm -rf /var/lib/apt/lists/*
ENV SQLITE_EXTENSIONS /usr/lib/x86_64-linux-gnu/mod_spatialite.so
"""


class QueryInterrupted(Exception):
    pass


class Results:
    def __init__(self, rows, truncated, description):
        self.rows = rows
        self.truncated = truncated
        self.description = description

    @property
    def columns(self):
        return [d[0] for d in self.description]

    def __iter__(self):
        return iter(self.rows)

    def __len__(self):
        return len(self.rows)


def urlsafe_components(token):
    "Splits token on commas and URL decodes each component"
    return [urllib.parse.unquote_plus(b) for b in token.split(",")]


def path_from_row_pks(row, pks, use_rowid, quote=True):
    """ Generate an optionally URL-quoted unique identifier
        for a row from its primary keys."""
    if use_rowid:
        bits = [row["rowid"]]
    else:
        bits = [
            row[pk]["value"] if isinstance(row[pk], dict) else row[pk] for pk in pks
        ]
    if quote:
        bits = [urllib.parse.quote_plus(str(bit)) for bit in bits]
    else:
        bits = [str(bit) for bit in bits]

    return ",".join(bits)


def compound_keys_after_sql(pks, start_index=0):
    # Implementation of keyset pagination
    # See https://github.com/simonw/datasette/issues/190
    # For pk1/pk2/pk3 returns:
    #
    # ([pk1] > :p0)
    #   or
    # ([pk1] = :p0 and [pk2] > :p1)
    #   or
    # ([pk1] = :p0 and [pk2] = :p1 and [pk3] > :p2)
    or_clauses = []
    pks_left = pks[:]
    while pks_left:
        and_clauses = []
        last = pks_left[-1]
        rest = pks_left[:-1]
        and_clauses = [
            "{} = :p{}".format(escape_sqlite(pk), (i + start_index))
            for i, pk in enumerate(rest)
        ]
        and_clauses.append(
            "{} > :p{}".format(escape_sqlite(last), (len(rest) + start_index))
        )
        or_clauses.append("({})".format(" and ".join(and_clauses)))
        pks_left.pop()
    or_clauses.reverse()
    return "({})".format("\n  or\n".join(or_clauses))


class CustomJSONEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, sqlite3.Row):
            return tuple(obj)
        if isinstance(obj, sqlite3.Cursor):
            return list(obj)
        if isinstance(obj, bytes):
            # Does it encode to utf8?
            try:
                return obj.decode("utf8")
            except UnicodeDecodeError:
                return {
                    "$base64": True,
                    "encoded": base64.b64encode(obj).decode("latin1"),
                }
        return json.JSONEncoder.default(self, obj)


@contextmanager
def sqlite_timelimit(conn, ms):
    deadline = time.time() + (ms / 1000)
    # n is the number of SQLite virtual machine instructions that will be
    # executed between each check. It's hard to know what to pick here.
    # After some experimentation, I've decided to go with 1000 by default and
    # 1 for time limits that are less than 50ms
    n = 1000
    if ms < 50:
        n = 1

    def handler():
        if time.time() >= deadline:
            return 1

    conn.set_progress_handler(handler, n)
    try:
        yield
    finally:
        conn.set_progress_handler(None, n)


class InvalidSql(Exception):
    pass


allowed_sql_res = [
    re.compile(r"^select\b"),
    re.compile(r"^explain select\b"),
    re.compile(r"^explain query plan select\b"),
    re.compile(r"^with\b"),
    re.compile(r"^explain with\b"),
    re.compile(r"^explain query plan with\b"),
]
disallawed_sql_res = [(re.compile("pragma"), "Statement may not contain PRAGMA")]


def validate_sql_select(sql):
    sql = "\n".join(
        line for line in sql.split("\n") if not line.strip().startswith("--")
    )
    sql = sql.strip().lower()
    if not any(r.match(sql) for r in allowed_sql_res):
        raise InvalidSql("Statement must be a SELECT")
    for r, msg in disallawed_sql_res:
        if r.search(sql):
            raise InvalidSql(msg)


def append_querystring(url, querystring):
    op = "&" if ("?" in url) else "?"
    return "{}{}{}".format(url, op, querystring)


def path_with_added_args(request, args, path=None):
    path = path or request.path
    if isinstance(args, dict):
        args = args.items()
    args_to_remove = {k for k, v in args if v is None}
    current = []
    for key, value in urllib.parse.parse_qsl(request.query_string):
        if key not in args_to_remove:
            current.append((key, value))
    current.extend([(key, value) for key, value in args if value is not None])
    query_string = urllib.parse.urlencode(current)
    if query_string:
        query_string = "?{}".format(query_string)
    return path + query_string


def path_with_removed_args(request, args, path=None):
    query_string = request.query_string
    if path is None:
        path = request.path
    else:
        if "?" in path:
            bits = path.split("?", 1)
            path, query_string = bits
    # args can be a dict or a set
    current = []
    if isinstance(args, set):

        def should_remove(key, value):
            return key in args

    elif isinstance(args, dict):
        # Must match key AND value
        def should_remove(key, value):
            return args.get(key) == value

    for key, value in urllib.parse.parse_qsl(query_string):
        if not should_remove(key, value):
            current.append((key, value))
    query_string = urllib.parse.urlencode(current)
    if query_string:
        query_string = "?{}".format(query_string)
    return path + query_string


def path_with_replaced_args(request, args, path=None):
    path = path or request.path
    if isinstance(args, dict):
        args = args.items()
    keys_to_replace = {p[0] for p in args}
    current = []
    for key, value in urllib.parse.parse_qsl(request.query_string):
        if key not in keys_to_replace:
            current.append((key, value))
    current.extend([p for p in args if p[1] is not None])
    query_string = urllib.parse.urlencode(current)
    if query_string:
        query_string = "?{}".format(query_string)
    return path + query_string


_css_re = re.compile(r"""['"\n\\]""")
_boring_keyword_re = re.compile(r"^[a-zA-Z_][a-zA-Z0-9_]*$")


def escape_css_string(s):
    return _css_re.sub(lambda m: "\\{:X}".format(ord(m.group())), s)


def escape_sqlite(s):
    if _boring_keyword_re.match(s) and (s.lower() not in reserved_words):
        return s
    else:
        return "[{}]".format(s)


def make_dockerfile(
    files,
    metadata_file,
    extra_options,
    branch,
    template_dir,
    plugins_dir,
    static,
    install,
    spatialite,
    version_note,
    environment_variables=None,
    port=8001,
):
    cmd = ["datasette", "serve", "--host", "0.0.0.0"]
    for filename in files:
        cmd.extend(["-i", filename])
    cmd.extend(["--cors", "--inspect-file", "inspect-data.json"])
    if metadata_file:
        cmd.extend(["--metadata", "{}".format(metadata_file)])
    if template_dir:
        cmd.extend(["--template-dir", "templates/"])
    if plugins_dir:
        cmd.extend(["--plugins-dir", "plugins/"])
    if version_note:
        cmd.extend(["--version-note", "{}".format(version_note)])
    if static:
        for mount_point, _ in static:
            cmd.extend(["--static", "{}:{}".format(mount_point, mount_point)])
    if extra_options:
        for opt in extra_options.split():
            cmd.append("{}".format(opt))
    cmd = [shlex.quote(part) for part in cmd]
    # port attribute is a (fixed) env variable and should not be quoted
    cmd.extend(["--port", "$PORT"])
    cmd = " ".join(cmd)
    if branch:
        install = [
            "https://github.com/simonw/datasette/archive/{}.zip".format(branch)
        ] + list(install)
    else:
        install = ["datasette"] + list(install)

    return """
FROM python:3.8
COPY . /app
WORKDIR /app
{spatialite_extras}
{environment_variables}
RUN pip install -U {install_from}
RUN datasette inspect {files} --inspect-file inspect-data.json
ENV PORT {port}
EXPOSE {port}
CMD {cmd}""".format(
        environment_variables="\n".join(
            [
                "ENV {} '{}'".format(key, value)
                for key, value in (environment_variables or {}).items()
            ]
        ),
        files=" ".join(files),
        cmd=cmd,
        install_from=" ".join(install),
        spatialite_extras=SPATIALITE_DOCKERFILE_EXTRAS if spatialite else "",
        port=port,
    ).strip()


@contextmanager
def temporary_docker_directory(
    files,
    name,
    metadata,
    extra_options,
    branch,
    template_dir,
    plugins_dir,
    static,
    install,
    spatialite,
    version_note,
    extra_metadata=None,
    environment_variables=None,
    port=8001,
):
    extra_metadata = extra_metadata or {}
    tmp = tempfile.TemporaryDirectory()
    # We create a datasette folder in there to get a nicer now deploy name
    datasette_dir = os.path.join(tmp.name, name)
    os.mkdir(datasette_dir)
    saved_cwd = os.getcwd()
    file_paths = [os.path.join(saved_cwd, file_path) for file_path in files]
    file_names = [os.path.split(f)[-1] for f in files]
    if metadata:
        metadata_content = parse_metadata(metadata.read())
    else:
        metadata_content = {}
    # Merge in the non-null values in extra_metadata
    mergedeep.merge(
        metadata_content,
        {key: value for key, value in extra_metadata.items() if value is not None},
    )
    try:
        dockerfile = make_dockerfile(
            file_names,
            metadata_content and "metadata.json",
            extra_options,
            branch,
            template_dir,
            plugins_dir,
            static,
            install,
            spatialite,
            version_note,
            environment_variables,
            port=port,
        )
        os.chdir(datasette_dir)
        if metadata_content:
            open("metadata.json", "w").write(json.dumps(metadata_content, indent=2))
        open("Dockerfile", "w").write(dockerfile)
        for path, filename in zip(file_paths, file_names):
            link_or_copy(path, os.path.join(datasette_dir, filename))
        if template_dir:
            link_or_copy_directory(
                os.path.join(saved_cwd, template_dir),
                os.path.join(datasette_dir, "templates"),
            )
        if plugins_dir:
            link_or_copy_directory(
                os.path.join(saved_cwd, plugins_dir),
                os.path.join(datasette_dir, "plugins"),
            )
        for mount_point, path in static:
            link_or_copy_directory(
                os.path.join(saved_cwd, path), os.path.join(datasette_dir, mount_point)
            )
        yield datasette_dir
    finally:
        tmp.cleanup()
        os.chdir(saved_cwd)


def detect_primary_keys(conn, table):
    " Figure out primary keys for a table. "
    table_info_rows = [
        row
        for row in conn.execute('PRAGMA table_info("{}")'.format(table)).fetchall()
        if row[-1]
    ]
    table_info_rows.sort(key=lambda row: row[-1])
    return [str(r[1]) for r in table_info_rows]


def get_outbound_foreign_keys(conn, table):
    infos = conn.execute("PRAGMA foreign_key_list([{}])".format(table)).fetchall()
    fks = []
    for info in infos:
        if info is not None:
            id, seq, table_name, from_, to_, on_update, on_delete, match = info
            fks.append(
                {"other_table": table_name, "column": from_, "other_column": to_}
            )
    return fks


def get_all_foreign_keys(conn):
    tables = [
        r[0] for r in conn.execute('select name from sqlite_master where type="table"')
    ]
    table_to_foreign_keys = {}
    for table in tables:
        table_to_foreign_keys[table] = {"incoming": [], "outgoing": []}
    for table in tables:
        infos = conn.execute("PRAGMA foreign_key_list([{}])".format(table)).fetchall()
        for info in infos:
            if info is not None:
                id, seq, table_name, from_, to_, on_update, on_delete, match = info
                if table_name not in table_to_foreign_keys:
                    # Weird edge case where something refers to a table that does
                    # not actually exist
                    continue
                table_to_foreign_keys[table_name]["incoming"].append(
                    {"other_table": table, "column": to_, "other_column": from_}
                )
                table_to_foreign_keys[table]["outgoing"].append(
                    {"other_table": table_name, "column": from_, "other_column": to_}
                )

    return table_to_foreign_keys


def detect_spatialite(conn):
    rows = conn.execute(
        'select 1 from sqlite_master where tbl_name = "geometry_columns"'
    ).fetchall()
    return len(rows) > 0


def detect_fts(conn, table):
    "Detect if table has a corresponding FTS virtual table and return it"
    rows = conn.execute(detect_fts_sql(table)).fetchall()
    if len(rows) == 0:
        return None
    else:
        return rows[0][0]


def detect_fts_sql(table):
    return r"""
        select name from sqlite_master
            where rootpage = 0
            and (
                sql like '%VIRTUAL TABLE%USING FTS%content="{table}"%'
                or sql like '%VIRTUAL TABLE%USING FTS%content=[{table}]%'
                or (
                    tbl_name = "{table}"
                    and sql like '%VIRTUAL TABLE%USING FTS%'
                )
            )
    """.format(
        table=table
    )


def detect_json1(conn=None):
    if conn is None:
        conn = sqlite3.connect(":memory:")
    try:
        conn.execute("SELECT json('{}')")
        return True
    except Exception:
        return False


def table_columns(conn, table):
    return [
        r[1]
        for r in conn.execute(
            "PRAGMA table_info({});".format(escape_sqlite(table))
        ).fetchall()
    ]


filter_column_re = re.compile(r"^_filter_column_\d+$")


def filters_should_redirect(special_args):
    redirect_params = []
    # Handle _filter_column=foo&_filter_op=exact&_filter_value=...
    filter_column = special_args.get("_filter_column")
    filter_op = special_args.get("_filter_op") or ""
    filter_value = special_args.get("_filter_value") or ""
    if "__" in filter_op:
        filter_op, filter_value = filter_op.split("__", 1)
    if filter_column:
        redirect_params.append(
            ("{}__{}".format(filter_column, filter_op), filter_value)
        )
    for key in ("_filter_column", "_filter_op", "_filter_value"):
        if key in special_args:
            redirect_params.append((key, None))
    # Now handle _filter_column_1=name&_filter_op_1=contains&_filter_value_1=hello
    column_keys = [k for k in special_args if filter_column_re.match(k)]
    for column_key in column_keys:
        number = column_key.split("_")[-1]
        column = special_args[column_key]
        op = special_args.get("_filter_op_{}".format(number)) or "exact"
        value = special_args.get("_filter_value_{}".format(number)) or ""
        if "__" in op:
            op, value = op.split("__", 1)
        if column:
            redirect_params.append(("{}__{}".format(column, op), value))
        redirect_params.extend(
            [
                ("_filter_column_{}".format(number), None),
                ("_filter_op_{}".format(number), None),
                ("_filter_value_{}".format(number), None),
            ]
        )
    return redirect_params


whitespace_re = re.compile(r"\s")


def is_url(value):
    "Must start with http:// or https:// and contain JUST a URL"
    if not isinstance(value, str):
        return False
    if not value.startswith("http://") and not value.startswith("https://"):
        return False
    # Any whitespace at all is invalid
    if whitespace_re.search(value):
        return False
    return True


css_class_re = re.compile(r"^[a-zA-Z]+[_a-zA-Z0-9-]*$")
css_invalid_chars_re = re.compile(r"[^a-zA-Z0-9_\-]")


def to_css_class(s):
    """
    Given a string (e.g. a table name) returns a valid unique CSS class.
    For simple cases, just returns the string again. If the string is not a
    valid CSS class (we disallow - and _ prefixes even though they are valid
    as they may be confused with browser prefixes) we strip invalid characters
    and add a 6 char md5 sum suffix, to make sure two tables with identical
    names after stripping characters don't end up with the same CSS class.
    """
    if css_class_re.match(s):
        return s
    md5_suffix = hashlib.md5(s.encode("utf8")).hexdigest()[:6]
    # Strip leading _, -
    s = s.lstrip("_").lstrip("-")
    # Replace any whitespace with hyphens
    s = "-".join(s.split())
    # Remove any remaining invalid characters
    s = css_invalid_chars_re.sub("", s)
    # Attach the md5 suffix
    bits = [b for b in (s, md5_suffix) if b]
    return "-".join(bits)


def link_or_copy(src, dst):
    # Intended for use in populating a temp directory. We link if possible,
    # but fall back to copying if the temp directory is on a different device
    # https://github.com/simonw/datasette/issues/141
    try:
        os.link(src, dst)
    except OSError:
        shutil.copyfile(src, dst)


def link_or_copy_directory(src, dst):
    try:
        shutil.copytree(src, dst, copy_function=os.link)
    except OSError:
        shutil.copytree(src, dst)


def module_from_path(path, name):
    # Adapted from http://sayspy.blogspot.com/2011/07/how-to-import-module-from-just-file.html
    mod = types.ModuleType(name)
    mod.__file__ = path
    with open(path, "r") as file:
        code = compile(file.read(), path, "exec", dont_inherit=True)
    exec(code, mod.__dict__)
    return mod


async def resolve_table_and_format(table_and_format, table_exists, allowed_formats=[]):
    if "." in table_and_format:
        # Check if a table exists with this exact name
        it_exists = await table_exists(table_and_format)
        if it_exists:
            return table_and_format, None

    # Check if table ends with a known format
    formats = list(allowed_formats) + ["csv", "jsono"]
    for _format in formats:
        if table_and_format.endswith(".{}".format(_format)):
            table = table_and_format[: -(len(_format) + 1)]
            return table, _format
    return table_and_format, None


def path_with_format(request, format, extra_qs=None):
    qs = extra_qs or {}
    path = request.path
    if "." in request.path:
        qs["_format"] = format
    else:
        path = "{}.{}".format(path, format)
    if qs:
        extra = urllib.parse.urlencode(sorted(qs.items()))
        if request.query_string:
            path = "{}?{}&{}".format(path, request.query_string, extra)
        else:
            path = "{}?{}".format(path, extra)
    elif request.query_string:
        path = "{}?{}".format(path, request.query_string)
    return path


class CustomRow(OrderedDict):
    # Loose imitation of sqlite3.Row which offers
    # both index-based AND key-based lookups
    def __init__(self, columns, values=None):
        self.columns = columns
        if values:
            self.update(values)

    def __getitem__(self, key):
        if isinstance(key, int):
            return super().__getitem__(self.columns[key])
        else:
            return super().__getitem__(key)

    def __iter__(self):
        for column in self.columns:
            yield self[column]


def value_as_boolean(value):
    if value.lower() not in ("on", "off", "true", "false", "1", "0"):
        raise ValueAsBooleanError
    return value.lower() in ("on", "true", "1")


class ValueAsBooleanError(ValueError):
    pass


class WriteLimitExceeded(Exception):
    pass


class LimitedWriter:
    def __init__(self, writer, limit_mb):
        self.writer = writer
        self.limit_bytes = limit_mb * 1024 * 1024
        self.bytes_count = 0

    async def write(self, bytes):
        self.bytes_count += len(bytes)
        if self.limit_bytes and (self.bytes_count > self.limit_bytes):
            raise WriteLimitExceeded(
                "CSV contains more than {} bytes".format(self.limit_bytes)
            )
        await self.writer.write(bytes)


_infinities = {float("inf"), float("-inf")}


def remove_infinites(row):
    if any((c in _infinities) if isinstance(c, float) else 0 for c in row):
        return [None if (isinstance(c, float) and c in _infinities) else c for c in row]
    return row


class StaticMount(click.ParamType):
    name = "mount:directory"

    def convert(self, value, param, ctx):
        if ":" not in value:
            self.fail(
                '"{}" should be of format mountpoint:directory'.format(value),
                param,
                ctx,
            )
        path, dirpath = value.split(":", 1)
        dirpath = os.path.abspath(dirpath)
        if not os.path.exists(dirpath) or not os.path.isdir(dirpath):
            self.fail("%s is not a valid directory path" % value, param, ctx)
        return path, dirpath


def format_bytes(bytes):
    current = float(bytes)
    for unit in ("bytes", "KB", "MB", "GB", "TB"):
        if current < 1024:
            break
        current = current / 1024
    if unit == "bytes":
        return "{} {}".format(int(current), unit)
    else:
        return "{:.1f} {}".format(current, unit)


_escape_fts_re = re.compile(r'\s+|(".*?")')


def escape_fts(query):
    # If query has unbalanced ", add one at end
    if query.count('"') % 2:
        query += '"'
    bits = _escape_fts_re.split(query)
    bits = [b for b in bits if b and b != '""']
    return " ".join(
        '"{}"'.format(bit) if not bit.startswith('"') else bit for bit in bits
    )


class RequestParameters(dict):
    def get(self, name, default=None):
        "Return first value in the list, if available"
        try:
            return super().get(name)[0]
        except (KeyError, TypeError):
            return default

    def getlist(self, name, default=None):
        "Return full list"
        return super().get(name, default)


class ConnectionProblem(Exception):
    pass


class SpatialiteConnectionProblem(ConnectionProblem):
    pass


def check_connection(conn):
    tables = [
        r[0]
        for r in conn.execute(
            "select name from sqlite_master where type='table'"
        ).fetchall()
    ]
    for table in tables:
        try:
            conn.execute("PRAGMA table_info({});".format(escape_sqlite(table)),)
        except sqlite3.OperationalError as e:
            if e.args[0] == "no such module: VirtualSpatialIndex":
                raise SpatialiteConnectionProblem(e)
            else:
                raise ConnectionProblem(e)


class BadMetadataError(Exception):
    pass


def parse_metadata(content):
    # content can be JSON or YAML
    try:
        return json.loads(content)
    except json.JSONDecodeError:
        try:
            return yaml.safe_load(content)
        except yaml.YAMLError:
            raise BadMetadataError("Metadata is not valid JSON or YAML")