#!/usr/bin/env python3
"""Build a de-duplicated 80th-percentile quality image union DB."""

from __future__ import annotations

import argparse
from collections import Counter
import json
import sqlite3
from pathlib import Path


PROJECT_ROOT = Path(__file__).resolve().parent
DEFAULT_GELBOORU_DB = PROJECT_ROOT / "gelbooru.db"
DEFAULT_DANBOORU_DB = PROJECT_ROOT / "danbooru2025_candidate.db"
DEFAULT_OUTPUT_DB = PROJECT_ROOT / "quality_80_union.db"

GEL_THRESHOLDS = {
    "sensitive": 17,
    "explicit": 125,
    "general": 6,
    "questionable": 61,
    "safe": 22,
}
DAN_THRESHOLDS = {
    "s": 31,
    "g": 16,
    "q": 70,
    "e": 110,
}
RATING_RANK = {
    "safe": 0,
    "general": 0,
    "sensitive": 1,
    "questionable": 2,
    "explicit": 3,
}


class BuildError(RuntimeError):
    pass


def dan_rating_name(value: str | None) -> str | None:
    return {"g": "general", "s": "sensitive", "q": "questionable", "e": "explicit"}.get(value, value)


def stricter_rating(left: str | None, right: str | None) -> str | None:
    if left is None:
        return right
    if right is None:
        return left
    return left if RATING_RANK.get(left, -1) >= RATING_RANK.get(right, -1) else right


def validate_output_path(output_db: Path, overwrite: bool) -> None:
    if output_db.exists() and not overwrite:
        raise BuildError(f"Output DB already exists: {output_db} (pass --overwrite to replace)")


def register_functions(conn: sqlite3.Connection) -> None:
    conn.create_function("dan_rating_name", 1, dan_rating_name)
    conn.create_function("stricter_rating", 2, stricter_rating)


def create_schema(conn: sqlite3.Connection) -> None:
    conn.executescript(
        """
        PRAGMA journal_mode=WAL;
        PRAGMA synchronous=OFF;
        PRAGMA cache_size=-1048576;

        CREATE TABLE selected_md5 (
            md5 TEXT PRIMARY KEY,
            selected_by_gelbooru80 INTEGER NOT NULL DEFAULT 0,
            selected_by_danbooru80 INTEGER NOT NULL DEFAULT 0
        );

        CREATE TABLE selected_gelbooru_posts (
            post_id INTEGER PRIMARY KEY,
            md5 TEXT NOT NULL
        );

        CREATE TABLE selected_danbooru_posts (
            post_id INTEGER PRIMARY KEY,
            md5 TEXT NOT NULL
        );

        CREATE TABLE images (
            md5 TEXT PRIMARY KEY,
            canonical_rating TEXT,
            canonical_file_url TEXT,
            canonical_preview_url TEXT,
            canonical_sample_url TEXT,
            canonical_source TEXT,
            canonical_width INTEGER,
            canonical_height INTEGER,
            present_in_gelbooru INTEGER NOT NULL,
            present_in_danbooru INTEGER NOT NULL,
            selected_by_gelbooru80 INTEGER NOT NULL,
            selected_by_danbooru80 INTEGER NOT NULL,
            quality_score REAL,
            quality_tier TEXT NOT NULL,
            gelbooru_id INTEGER,
            gelbooru_rating TEXT,
            gelbooru_score INTEGER,
            gelbooru_score_pct REAL,
            gelbooru_file_url TEXT,
            gelbooru_preview_url TEXT,
            gelbooru_sample_url TEXT,
            gelbooru_source TEXT,
            gelbooru_tags_text TEXT,
            gelbooru_status TEXT,
            danbooru_id INTEGER,
            danbooru_rating TEXT,
            danbooru_score INTEGER,
            danbooru_score_pct REAL,
            danbooru_file_url TEXT,
            danbooru_source TEXT,
            danbooru_pixiv_id INTEGER,
            danbooru_fav_count INTEGER,
            danbooru_file_size INTEGER,
            danbooru_file_ext TEXT,
            image_parquet_file TEXT
        );

        CREATE TABLE gelbooru_image_tags (
            md5 TEXT NOT NULL REFERENCES images(md5),
            tag_name TEXT NOT NULL,
            PRIMARY KEY (md5, tag_name)
        ) WITHOUT ROWID;

        CREATE TABLE danbooru_image_tags (
            md5 TEXT NOT NULL REFERENCES images(md5),
            tag_name TEXT NOT NULL,
            tag_type TEXT NOT NULL,
            PRIMARY KEY (md5, tag_name, tag_type)
        ) WITHOUT ROWID;

        CREATE TABLE build_metadata (
            key TEXT PRIMARY KEY,
            value TEXT
        );

        CREATE TABLE gel_score_percentiles (
            rating TEXT NOT NULL,
            score INTEGER NOT NULL,
            pct REAL NOT NULL,
            PRIMARY KEY (rating, score)
        ) WITHOUT ROWID;

        CREATE TABLE dan_score_percentiles (
            rating TEXT NOT NULL,
            score INTEGER NOT NULL,
            pct REAL NOT NULL,
            PRIMARY KEY (rating, score)
        ) WITHOUT ROWID;
        """
    )


TAG_BATCH_SIZE = 50000
PERCENTILE_INSERT_BATCH_SIZE = 5000


def _identity_rating(value: str | None) -> str | None:
    return value


def _score_percentile_rows(histogram: dict[str, Counter[int]]) -> list[tuple[str, int, float]]:
    rows: list[tuple[str, int, float]] = []
    for rating, counts in histogram.items():
        total = sum(counts.values())
        cumulative = 0
        for score in sorted(counts):
            cumulative += counts[score]
            rows.append((rating, score, cumulative / total))
    return rows


def _populate_score_percentiles(
    conn: sqlite3.Connection,
    source_db_alias: str,
    dest_table: str,
    normalize_rating,
) -> int:
    """Build cume_dist score lookup with O(unique scores) memory."""
    histogram: dict[str, Counter[int]] = {}
    cursor = conn.execute(
        f"""
        SELECT rating, score
        FROM {source_db_alias}.posts
        WHERE md5 IS NOT NULL AND md5 <> ''
          AND score IS NOT NULL
        """
    )
    for raw_rating, score in cursor:
        rating = normalize_rating(raw_rating)
        if rating is None:
            continue
        histogram.setdefault(rating, Counter())[int(score)] += 1

    rows = _score_percentile_rows(histogram)
    conn.executemany(
        f"INSERT INTO {dest_table}(rating, score, pct) VALUES (?, ?, ?)",
        rows,
    )
    conn.commit()
    return len(rows)


def _batch_insert_tags(
    conn: sqlite3.Connection,
    src_posts_table: str,
    dest_table: str,
    dest_cols: str,
    src_db_alias: str,
) -> int:
    """Insert tags for selected posts in batches, committing per batch."""
    post_count = conn.execute(
        f"SELECT COUNT(*) FROM {src_posts_table}"
    ).fetchone()[0]
    total = 0
    offset = 0
    batch = 0
    tag_type_col = ", t.type" if ", tag_type" in dest_cols else ""
    while offset < post_count:
        batch += 1
        before_changes = conn.total_changes
        conn.execute(
            f"""
            INSERT OR IGNORE INTO {dest_table}({dest_cols})
            SELECT p.md5, t.name{tag_type_col}
            FROM (
                SELECT post_id, md5 FROM {src_posts_table}
                LIMIT {TAG_BATCH_SIZE} OFFSET {offset}
            ) p
            CROSS JOIN {src_db_alias}.post_tags pt ON pt.post_id = p.post_id
            JOIN {src_db_alias}.tags t ON t.id = pt.tag_id
            """
        )
        conn.commit()
        total += conn.total_changes - before_changes
        offset += TAG_BATCH_SIZE
        if batch % 10 == 0 or offset >= post_count:
            pct = min(100, offset * 100 // post_count)
            print(f"  [{src_db_alias}] tags batch {batch}: {offset:,}/{post_count:,} posts ({pct}%)")
    return total


def build_quality_db(gelbooru_db: Path, danbooru_db: Path, output_db: Path, overwrite: bool) -> dict:
    output_db = output_db.resolve()
    validate_output_path(output_db, overwrite)
    building_path = output_db.with_suffix(output_db.suffix + ".building")
    if building_path.exists():
        building_path.unlink()
    conn = sqlite3.connect(building_path)
    register_functions(conn)
    create_schema(conn)
    conn.execute("ATTACH DATABASE ? AS g", (str(gelbooru_db),))
    conn.execute("ATTACH DATABASE ? AS d", (str(danbooru_db),))

    print("[1/7] Building rating-bucket score percentiles...")
    gel_pct_rows = _populate_score_percentiles(conn, "g", "gel_score_percentiles", _identity_rating)
    dan_pct_rows = _populate_score_percentiles(conn, "d", "dan_score_percentiles", dan_rating_name)
    print(f"  Gelbooru: {gel_pct_rows:,} score buckets, Danbooru: {dan_pct_rows:,} score buckets")

    print("[2/7] Selecting md5 by 80th percentile thresholds...")
    gel_count = conn.execute(
        """
        INSERT INTO selected_md5(md5, selected_by_gelbooru80, selected_by_danbooru80)
        SELECT md5, 1, 0
        FROM g.posts
        WHERE md5 IS NOT NULL AND md5 <> ''
          AND score >= CASE rating
            WHEN 'sensitive' THEN 17
            WHEN 'explicit' THEN 125
            WHEN 'general' THEN 6
            WHEN 'questionable' THEN 61
            WHEN 'safe' THEN 22
            ELSE 999999999
          END
        """
    ).rowcount
    print(f"  Gelbooru 80th: {gel_count:,} md5")

    dan_count = conn.execute(
        """
        INSERT INTO selected_md5(md5, selected_by_gelbooru80, selected_by_danbooru80)
        SELECT md5, 0, 1
        FROM d.posts
        WHERE md5 IS NOT NULL AND md5 <> ''
          AND score >= CASE rating
            WHEN 's' THEN 31
            WHEN 'g' THEN 16
            WHEN 'q' THEN 70
            WHEN 'e' THEN 110
            ELSE 999999999
          END
        ON CONFLICT(md5) DO UPDATE SET selected_by_danbooru80 = 1
        """
    ).rowcount
    union = conn.execute("SELECT COUNT(*) FROM selected_md5").fetchone()[0]
    both = conn.execute(
        "SELECT COUNT(*) FROM selected_md5 WHERE selected_by_gelbooru80=1 AND selected_by_danbooru80=1"
    ).fetchone()[0]
    print(f"  Danbooru 80th: {dan_count:,} md5")
    print(f"  Union: {union:,} unique md5 ({both:,} in both)")
    conn.commit()

    print("[3/7] Mapping selected posts...")
    gel_posts = conn.execute(
        """
        INSERT INTO selected_gelbooru_posts(post_id, md5)
        SELECT gp.id, gp.md5
        FROM selected_md5 s
        JOIN g.posts gp ON gp.md5 = s.md5
        """
    ).rowcount
    dan_posts = conn.execute(
        """
        INSERT INTO selected_danbooru_posts(post_id, md5)
        SELECT dp.id, dp.md5
        FROM selected_md5 s
        JOIN d.posts dp ON dp.md5 = s.md5
        """
    ).rowcount
    print(f"  Gelbooru: {gel_posts:,} posts, Danbooru: {dan_posts:,} posts")
    conn.commit()

    print("[4/7] Merging into images table...")
    img_count = conn.execute(
        """
        INSERT INTO images (
            md5, canonical_rating, canonical_file_url, canonical_preview_url, canonical_sample_url,
            canonical_source, canonical_width, canonical_height,
            present_in_gelbooru, present_in_danbooru,
            selected_by_gelbooru80, selected_by_danbooru80,
            quality_score, quality_tier,
            gelbooru_id, gelbooru_rating, gelbooru_score, gelbooru_score_pct,
            gelbooru_file_url, gelbooru_preview_url, gelbooru_sample_url,
            gelbooru_source, gelbooru_tags_text, gelbooru_status,
            danbooru_id, danbooru_rating, danbooru_score, danbooru_score_pct,
            danbooru_file_url, danbooru_source, danbooru_pixiv_id,
            danbooru_fav_count, danbooru_file_size, danbooru_file_ext
        )
        SELECT
            s.md5,
            stricter_rating(gp.rating, dan_rating_name(dp.rating)),
            COALESCE(gp.file_url, dp.file_url),
            gp.preview_url,
            gp.sample_url,
            COALESCE(gp.source, dp.source),
            COALESCE(gp.width, dp.image_width),
            COALESCE(gp.height, dp.image_height),
            CASE WHEN gp.id IS NULL THEN 0 ELSE 1 END,
            CASE WHEN dp.id IS NULL THEN 0 ELSE 1 END,
            s.selected_by_gelbooru80,
            s.selected_by_danbooru80,
            max(COALESCE(gsp.pct, 0), COALESCE(dsp.pct, 0)),
            'p80',
            gp.id, gp.rating, gp.score, gsp.pct,
            gp.file_url, gp.preview_url, gp.sample_url, gp.source, gp.tags, gp.status,
            dp.id, dan_rating_name(dp.rating), dp.score, dsp.pct,
            dp.file_url, dp.source, dp.pixiv_id, dp.fav_count, dp.file_size, dp.file_ext
        FROM selected_md5 s
        LEFT JOIN g.posts gp ON gp.md5 = s.md5
        LEFT JOIN d.posts dp ON dp.md5 = s.md5
        LEFT JOIN gel_score_percentiles gsp ON gsp.rating = gp.rating AND gsp.score = gp.score
        LEFT JOIN dan_score_percentiles dsp ON dsp.rating = dan_rating_name(dp.rating) AND dsp.score = dp.score
        """
    ).rowcount
    print(f"  {img_count:,} images written")
    conn.commit()

    print("[5/7] Inserting Gelbooru tags (batched)...")
    gel_tag_count = _batch_insert_tags(
        conn,
        src_posts_table="selected_gelbooru_posts",
        dest_table="gelbooru_image_tags",
        dest_cols="md5, tag_name",
        src_db_alias="g",
    )
    print(f"  {gel_tag_count:,} gelbooru tag associations")

    print("[6/7] Inserting Danbooru tags (batched)...")
    dan_tag_count = _batch_insert_tags(
        conn,
        src_posts_table="selected_danbooru_posts",
        dest_table="danbooru_image_tags",
        dest_cols="md5, tag_name, tag_type",
        src_db_alias="d",
    )
    print(f"  {dan_tag_count:,} danbooru tag associations")

    print("[7/7] Creating indexes and finalizing...")
    create_indexes(conn)
    summary = validate_built_db(conn)
    metadata = {
        "gelbooru_db": str(gelbooru_db),
        "danbooru_db": str(danbooru_db),
        "gel_thresholds": json.dumps(GEL_THRESHOLDS, sort_keys=True),
        "dan_thresholds": json.dumps(DAN_THRESHOLDS, sort_keys=True),
        "quality_score_method": "rating_bucket_cume_dist_v1",
        "quality_score_scale": "0..1",
        **{k: str(v) for k, v in summary.items()},
    }
    conn.executemany("INSERT INTO build_metadata(key, value) VALUES (?, ?)", metadata.items())
    conn.commit()
    conn.close()
    if output_db.exists():
        output_db.unlink()
    building_path.rename(output_db)
    return summary


def create_indexes(conn: sqlite3.Connection) -> None:
    conn.executescript(
        """
        CREATE INDEX idx_images_canonical_rating ON images(canonical_rating);
        CREATE INDEX idx_images_quality_score ON images(quality_score);
        CREATE INDEX idx_images_present_sources ON images(present_in_gelbooru, present_in_danbooru);
        CREATE INDEX idx_images_selected_sources ON images(selected_by_gelbooru80, selected_by_danbooru80);
        CREATE INDEX idx_gelbooru_image_tags_tag ON gelbooru_image_tags(tag_name);
        CREATE INDEX idx_danbooru_image_tags_tag_type ON danbooru_image_tags(tag_name, tag_type);
        """
    )
    conn.commit()


def validate_built_db(conn: sqlite3.Connection) -> dict:
    images = conn.execute("SELECT COUNT(*) FROM images").fetchone()[0]
    distinct_md5 = conn.execute("SELECT COUNT(DISTINCT md5) FROM images").fetchone()[0]
    if images != distinct_md5:
        raise BuildError(f"md5 de-duplication failed: images={images}, distinct_md5={distinct_md5}")
    selected_by_gel = conn.execute("SELECT COUNT(*) FROM images WHERE selected_by_gelbooru80 = 1").fetchone()[0]
    selected_by_dan = conn.execute("SELECT COUNT(*) FROM images WHERE selected_by_danbooru80 = 1").fetchone()[0]
    selected_by_both = conn.execute(
        "SELECT COUNT(*) FROM images WHERE selected_by_gelbooru80 = 1 AND selected_by_danbooru80 = 1"
    ).fetchone()[0]
    return {
        "images": images,
        "selected_by_gelbooru80": selected_by_gel,
        "selected_by_danbooru80": selected_by_dan,
        "selected_by_both": selected_by_both,
        "gelbooru_image_tags": conn.execute("SELECT COUNT(*) FROM gelbooru_image_tags").fetchone()[0],
        "danbooru_image_tags": conn.execute("SELECT COUNT(*) FROM danbooru_image_tags").fetchone()[0],
    }


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--gelbooru-db", type=Path, default=DEFAULT_GELBOORU_DB)
    parser.add_argument("--danbooru-db", type=Path, default=DEFAULT_DANBOORU_DB)
    parser.add_argument("--output-db", type=Path, default=DEFAULT_OUTPUT_DB)
    parser.add_argument("--overwrite", action="store_true")
    parser.add_argument("--json", action="store_true")
    return parser.parse_args()


def main() -> None:
    args = parse_args()
    summary = build_quality_db(args.gelbooru_db, args.danbooru_db, args.output_db, args.overwrite)
    if args.json:
        print(json.dumps(summary, ensure_ascii=False, indent=2))
    else:
        print(f"\nDone. {summary['images']:,} images, "
              f"{summary['gelbooru_image_tags']:,} gel tags, "
              f"{summary['danbooru_image_tags']:,} dan tags")


if __name__ == "__main__":
    try:
        main()
    except BuildError as exc:
        raise SystemExit(f"error: {exc}")