import sqlite3
from functools import partial
from itertools import islice
from pathlib import Path

import click

BATCH_SIZE=1024


@click.command()
@click.argument('input_dir', type=click.Path(exists=True, file_okay=False, path_type=Path))
@click.argument('output', type=click.Path(dir_okay=False, writable=True, path_type=Path))
@click.option('--image-host', help="base URL of images")
@click.option('--explicit/--no-explicit', default=False)
def main(input_dir: Path, output: Path, image_host: str, explicit:bool):
    connection = sqlite3.connect(output)
    try:
        _main_with_connection(input_dir, connection, image_host, explicit)
    finally:
        connection.close()

def _main_with_connection(input_dir: Path, connection: sqlite3.Connection, image_host: str=None, explicit=False):
    connection.execute("CREATE TABLE IF NOT EXISTS "
                       "    captions(image_key text PRIMARY KEY, caption text NOT NULL);")

    if image_host:
        connection.execute(f"""
        CREATE VIEW IF NOT EXISTS images AS
            SELECT {sql_quote(connection, image_host)} || image_key || '.jpg' AS image,
            caption, 
            rowid
        FROM captions
        """)

    text_files = input_dir.glob("*.txt")

    with click.progressbar(chunked(text_files, BATCH_SIZE)) as progress:
        for batch in progress:
            text_file: Path
            pairs = ((text_file.stem, text_file.read_text())
                for text_file in batch)
            with connection:
                connection.executemany("INSERT INTO captions(image_key, caption) "
                                       "VALUES(?, ?) ", pairs)

    if not explicit:
        ratings = ["rating:unsafe", "rating:explicit", "rating:mature", "meta:nsfw",
                   "subreddit:%nsfw"]
        for rating in ratings:
            with connection:
                c = connection.execute("DELETE FROM captions WHERE caption LIKE ?",
                                       (f"%{rating}%",))
                print(f"Removed {c.rowcount} {rating} rows")

    with connection:
        # Add full-text search index
        connection.execute("""CREATE VIRTUAL TABLE
           captions_fts USING 
           fts5(caption, image_key UNINDEXED, content=captions)
        """)
        connection.execute("""
            INSERT INTO "captions_fts" (rowid, image_key, caption)
            SELECT rowid, image_key, caption
            FROM captions
        """)


def chunked(iterable, n):
    return iter(partial(take, n, iter(iterable)), [])

def take(n, iterable):
    return list(islice(iterable, n))

def sql_quote(connection, value: str) -> str:
    """
    Apply SQLite string quoting to a value, including wrapping it in single quotes.
    :param value: String to quote
    """
    # Normally we would use .execute(sql, [params]) for escaping, but
    # occasionally that isn't available - most notable when we need
    # to include a "... DEFAULT 'value'" in a column definition.
    return connection.execute(
        # Use SQLite itself to correctly escape this string:
        "SELECT quote(:value)",
        {"value": value},
    ).fetchone()[0]

if __name__ == "__main__":
    main()