import hashlib
import itertools
import json
import os
import sqlite3
import sys
import traceback
import urllib.parse
from concurrent import futures
from pathlib import Path

import pluggy
from jinja2 import ChoiceLoader, Environment, FileSystemLoader, PrefixLoader
from sanic import Sanic, response
from sanic.exceptions import InvalidUsage, NotFound

from datasette.views.base import (
    HASH_BLOCK_SIZE,
    DatasetteError,
    RenderMixin,
    ureg
)
from datasette.views.database import DatabaseDownload, DatabaseView
from datasette.views.index import IndexView
from datasette.views.table import RowView, TableView

from . import hookspecs
from .utils import (
    detect_fts,
    detect_spatialite,
    escape_css_string,
    escape_sqlite,
    get_all_foreign_keys,
    get_plugins,
    module_from_path,
    to_css_class
)
from .version import __version__

app_root = Path(__file__).parent.parent


pm = pluggy.PluginManager("datasette")
pm.add_hookspecs(hookspecs)
pm.load_setuptools_entrypoints("datasette")


class JsonDataView(RenderMixin):

    def __init__(self, datasette, filename, data_callback):
        self.ds = datasette
        self.jinja_env = datasette.jinja_env
        self.filename = filename
        self.data_callback = data_callback

    async def get(self, request, as_json):
        data = self.data_callback()
        if as_json:
            headers = {}
            if self.ds.cors:
                headers["Access-Control-Allow-Origin"] = "*"
            return response.HTTPResponse(
                json.dumps(data), content_type="application/json", headers=headers
            )

        else:
            return self.render(["show_json.html"], filename=self.filename, data=data)


async def favicon(request):
    return response.text("")


class Datasette:

    def __init__(
        self,
        files,
        num_threads=3,
        cache_headers=True,
        page_size=100,
        max_returned_rows=1000,
        sql_time_limit_ms=1000,
        cors=False,
        inspect_data=None,
        metadata=None,
        sqlite_extensions=None,
        template_dir=None,
        plugins_dir=None,
        static_mounts=None,
    ):
        self.files = files
        self.num_threads = num_threads
        self.executor = futures.ThreadPoolExecutor(max_workers=num_threads)
        self.cache_headers = cache_headers
        self.page_size = page_size
        self.max_returned_rows = max_returned_rows
        self.sql_time_limit_ms = sql_time_limit_ms
        self.cors = cors
        self._inspect = inspect_data
        self.metadata = metadata or {}
        self.sqlite_functions = []
        self.sqlite_extensions = sqlite_extensions or []
        self.template_dir = template_dir
        self.plugins_dir = plugins_dir
        self.static_mounts = static_mounts or []
        # Execute plugins in constructor, to ensure they are available
        # when the rest of `datasette inspect` executes
        if self.plugins_dir:
            for filename in os.listdir(self.plugins_dir):
                filepath = os.path.join(self.plugins_dir, filename)
                mod = module_from_path(filepath, name=filename)
                try:
                    pm.register(mod)
                except ValueError:
                    # Plugin already registered
                    pass

    def app_css_hash(self):
        if not hasattr(self, "_app_css_hash"):
            self._app_css_hash = hashlib.sha1(
                open(
                    os.path.join(str(app_root), "datasette/static/app.css")
                ).read().encode(
                    "utf8"
                )
            ).hexdigest()[
                :6
            ]
        return self._app_css_hash

    def get_canned_query(self, database_name, query_name):
        query = self.metadata.get("databases", {}).get(database_name, {}).get(
            "queries", {}
        ).get(
            query_name
        )
        if query:
            return {"name": query_name, "sql": query}

    def asset_urls(self, key):
        urls_or_dicts = (self.metadata.get(key) or [])
        # Flatten list-of-lists from plugins:
        urls_or_dicts += list(itertools.chain.from_iterable(getattr(pm.hook, key)()))
        for url_or_dict in urls_or_dicts:
            if isinstance(url_or_dict, dict):
                yield {"url": url_or_dict["url"], "sri": url_or_dict.get("sri")}

            else:
                yield {"url": url_or_dict}

    def extra_css_urls(self):
        return self.asset_urls("extra_css_urls")

    def extra_js_urls(self):
        return self.asset_urls("extra_js_urls")

    def update_with_inherited_metadata(self, metadata):
        # Fills in source/license with defaults, if available
        metadata.update(
            {
                "source": metadata.get("source") or self.metadata.get("source"),
                "source_url": metadata.get("source_url")
                or self.metadata.get("source_url"),
                "license": metadata.get("license") or self.metadata.get("license"),
                "license_url": metadata.get("license_url")
                or self.metadata.get("license_url"),
            }
        )

    def prepare_connection(self, conn):
        conn.row_factory = sqlite3.Row
        conn.text_factory = lambda x: str(x, "utf-8", "replace")
        for name, num_args, func in self.sqlite_functions:
            conn.create_function(name, num_args, func)
        if self.sqlite_extensions:
            conn.enable_load_extension(True)
            for extension in self.sqlite_extensions:
                conn.execute("SELECT load_extension('{}')".format(extension))
        pm.hook.prepare_connection(conn=conn)

    def inspect(self):
        if not self._inspect:
            self._inspect = {}
            for filename in self.files:
                path = Path(filename)
                name = path.stem
                if name in self._inspect:
                    raise Exception("Multiple files with same stem %s" % name)

                # Calculate hash, efficiently
                m = hashlib.sha256()
                with path.open("rb") as fp:
                    while True:
                        data = fp.read(HASH_BLOCK_SIZE)
                        if not data:
                            break

                        m.update(data)
                # List tables and their row counts
                database_metadata = self.metadata.get("databases", {}).get(name, {})
                tables = {}
                views = []
                with sqlite3.connect(
                    "file:{}?immutable=1".format(path), uri=True
                ) as conn:
                    self.prepare_connection(conn)
                    table_names = [
                        r["name"]
                        for r in conn.execute(
                            'select * from sqlite_master where type="table"'
                        )
                    ]
                    views = [
                        v[0]
                        for v in conn.execute(
                            'select name from sqlite_master where type = "view"'
                        )
                    ]
                    for table in table_names:
                        try:
                            count = conn.execute(
                                "select count(*) from {}".format(escape_sqlite(table))
                            ).fetchone()[
                                0
                            ]
                        except sqlite3.OperationalError:
                            # This can happen when running against a FTS virtual tables
                            # e.g. "select count(*) from some_fts;"
                            count = 0
                        # Does this table have a FTS table?
                        fts_table = detect_fts(conn, table)

                        # Figure out primary keys
                        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])
                        primary_keys = [str(r[1]) for r in table_info_rows]
                        label_column = None
                        # If table has two columns, one of which is ID, then label_column is the other one
                        column_names = [
                            r[1]
                            for r in conn.execute(
                                "PRAGMA table_info({});".format(escape_sqlite(table))
                            ).fetchall()
                        ]
                        if (
                            column_names
                            and len(column_names) == 2
                            and "id" in column_names
                        ):
                            label_column = [c for c in column_names if c != "id"][0]
                        table_metadata = database_metadata.get("tables", {}).get(
                            table, {}
                        )
                        tables[table] = {
                            "name": table,
                            "columns": column_names,
                            "primary_keys": primary_keys,
                            "count": count,
                            "label_column": label_column,
                            "hidden": table_metadata.get("hidden") or False,
                            "fts_table": fts_table,
                        }

                    foreign_keys = get_all_foreign_keys(conn)
                    for table, info in foreign_keys.items():
                        tables[table]["foreign_keys"] = info

                    # Mark tables 'hidden' if they relate to FTS virtual tables
                    hidden_tables = [
                        r["name"]
                        for r in conn.execute(
                            """
                                select name from sqlite_master
                                where rootpage = 0
                                and sql like '%VIRTUAL TABLE%USING FTS%'
                            """
                        )
                    ]

                    if detect_spatialite(conn):
                        # Also hide Spatialite internal tables
                        hidden_tables += [
                            "ElementaryGeometries",
                            "SpatialIndex",
                            "geometry_columns",
                            "spatial_ref_sys",
                            "spatialite_history",
                            "sql_statements_log",
                            "sqlite_sequence",
                            "views_geometry_columns",
                            "virts_geometry_columns",
                        ] + [
                            r["name"]
                            for r in conn.execute(
                                """
                                    select name from sqlite_master
                                    where name like "idx_%"
                                    and type = "table"
                                """
                            )
                        ]

                    for t in tables.keys():
                        for hidden_table in hidden_tables:
                            if t == hidden_table or t.startswith(hidden_table):
                                tables[t]["hidden"] = True
                                continue

                self._inspect[name] = {
                    "hash": m.hexdigest(),
                    "file": str(path),
                    "tables": tables,
                    "views": views,
                }
        return self._inspect

    def register_custom_units(self):
        "Register any custom units defined in the metadata.json with Pint"
        for unit in self.metadata.get("custom_units", []):
            ureg.define(unit)

    def versions(self):
        conn = sqlite3.connect(":memory:")
        self.prepare_connection(conn)
        sqlite_version = conn.execute("select sqlite_version()").fetchone()[0]
        sqlite_extensions = {}
        for extension, testsql, hasversion in (
            ("json1", "SELECT json('{}')", False),
            ("spatialite", "SELECT spatialite_version()", True),
        ):
            try:
                result = conn.execute(testsql)
                if hasversion:
                    sqlite_extensions[extension] = result.fetchone()[0]
                else:
                    sqlite_extensions[extension] = None
            except Exception as e:
                pass
        # Figure out supported FTS versions
        fts_versions = []
        for fts in ("FTS5", "FTS4", "FTS3"):
            try:
                conn.execute(
                    "CREATE VIRTUAL TABLE v{fts} USING {fts} (t TEXT)".format(fts=fts)
                )
                fts_versions.append(fts)
            except sqlite3.OperationalError:
                continue

        return {
            "python": {
                "version": ".".join(map(str, sys.version_info[:3])), "full": sys.version
            },
            "datasette": {"version": __version__},
            "sqlite": {
                "version": sqlite_version,
                "fts_versions": fts_versions,
                "extensions": sqlite_extensions,
            },
        }

    def plugins(self):
        return [
            {
                "name": p["name"],
                "static": p["static_path"] is not None,
                "templates": p["templates_path"] is not None,
                "version": p.get("version"),
            }
            for p in get_plugins(pm)
        ]

    def app(self):
        app = Sanic(__name__)
        default_templates = str(app_root / "datasette" / "templates")
        template_paths = []
        if self.template_dir:
            template_paths.append(self.template_dir)
        template_paths.extend(
            [
                plugin["templates_path"]
                for plugin in get_plugins(pm)
                if plugin["templates_path"]
            ]
        )
        template_paths.append(default_templates)
        template_loader = ChoiceLoader(
            [
                FileSystemLoader(template_paths),
                # Support {% extends "default:table.html" %}:
                PrefixLoader(
                    {"default": FileSystemLoader(default_templates)}, delimiter=":"
                ),
            ]
        )
        self.jinja_env = Environment(loader=template_loader, autoescape=True)
        self.jinja_env.filters["escape_css_string"] = escape_css_string
        self.jinja_env.filters["quote_plus"] = lambda u: urllib.parse.quote_plus(u)
        self.jinja_env.filters["escape_sqlite"] = escape_sqlite
        self.jinja_env.filters["to_css_class"] = to_css_class
        pm.hook.prepare_jinja2_environment(env=self.jinja_env)
        app.add_route(IndexView.as_view(self), "/<as_json:(\.jsono?)?$>")
        # TODO: /favicon.ico and /-/static/ deserve far-future cache expires
        app.add_route(favicon, "/favicon.ico")
        app.static("/-/static/", str(app_root / "datasette" / "static"))
        for path, dirname in self.static_mounts:
            app.static(path, dirname)
        # Mount any plugin static/ directories
        for plugin in get_plugins(pm):
            if plugin["static_path"]:
                modpath = "/-/static-plugins/{}/".format(plugin["name"])
                app.static(modpath, plugin["static_path"])
        app.add_route(
            JsonDataView.as_view(self, "inspect.json", self.inspect),
            "/-/inspect<as_json:(\.json)?$>",
        )
        app.add_route(
            JsonDataView.as_view(self, "metadata.json", lambda: self.metadata),
            "/-/metadata<as_json:(\.json)?$>",
        )
        app.add_route(
            JsonDataView.as_view(self, "versions.json", self.versions),
            "/-/versions<as_json:(\.json)?$>",
        )
        app.add_route(
            JsonDataView.as_view(self, "plugins.json", self.plugins),
            "/-/plugins<as_json:(\.json)?$>",
        )
        app.add_route(
            DatabaseView.as_view(self), "/<db_name:[^/\.]+?><as_json:(\.jsono?)?$>"
        )
        app.add_route(
            DatabaseDownload.as_view(self), "/<db_name:[^/]+?><as_db:(\.db)$>"
        )
        app.add_route(
            TableView.as_view(self),
            "/<db_name:[^/]+>/<table:[^/]+?><as_json:(\.jsono?)?$>",
        )
        app.add_route(
            RowView.as_view(self),
            "/<db_name:[^/]+>/<table:[^/]+?>/<pk_path:[^/]+?><as_json:(\.jsono?)?$>",
        )

        self.register_custom_units()

        @app.exception(Exception)
        def on_exception(request, exception):
            title = None
            if isinstance(exception, NotFound):
                status = 404
                info = {}
                message = exception.args[0]
            elif isinstance(exception, InvalidUsage):
                status = 405
                info = {}
                message = exception.args[0]
            elif isinstance(exception, DatasetteError):
                status = exception.status
                info = exception.error_dict
                message = exception.message
                title = exception.title
            else:
                status = 500
                info = {}
                message = str(exception)
                traceback.print_exc()
            templates = ["500.html"]
            if status != 500:
                templates = ["{}.html".format(status)] + templates
            info.update(
                {"ok": False, "error": message, "status": status, "title": title}
            )
            if request.path.split("?")[0].endswith(".json"):
                return response.json(info, status=status)

            else:
                template = self.jinja_env.select_template(templates)
                return response.html(template.render(info), status=status)

        return app