#!/usr/bin/env python3
"""Migrate legacy contract templates from docauditai to leaudit_platform."""

from __future__ import annotations

import argparse
import asyncio
from dataclasses import dataclass
from io import BytesIO
from pathlib import Path

import asyncpg
from minio import Minio

from fastapi_common.fastapi_common_storage.oss_path_utils import OssPathUtils


ROOT = Path(__file__).resolve().parents[1]
APP_TOML = ROOT / "app.toml"
OLD_BUCKET = "docauditai"


@dataclass(frozen=True)
class LegacyCategory:
    id: int
    name: str
    icon: str | None
    description: str | None
    sort_order: int


@dataclass(frozen=True)
class LegacyTemplate:
    id: int
    template_code: str
    title: str
    category_id: int
    description: str | None
    file_path: str | None
    file_format: str | None
    is_featured: bool | None
    created_at: object
    updated_at: object
    pdf_file_path: str | None
    category_name: str


def load_target_config() -> dict[str, str]:
    try:
        import tomllib
    except ImportError:  # pragma: no cover
        import tomli as tomllib

    with APP_TOML.open("rb") as fh:
        config = tomllib.load(fh)

    db = config["DB"]
    oss = config["OSS"]
    return {
        "target_dsn": (
            f"postgresql://{db['USER']}:{db['PASSWORD']}"
            f"@{db['HOST']}:{db['PORT']}/{db['NAME']}"
        ),
        "oss_endpoint": oss["ENDPOINT"],
        "oss_base_url": oss.get("BASE_URL", ""),
        "oss_access_key": oss["ACCESS_KEY"],
        "oss_secret_key": oss["SECRET_KEY"],
        "oss_bucket": oss["BUCKET"],
    }


def build_legacy_dsn(args: argparse.Namespace) -> str:
    return (
        f"postgresql://{args.legacy_user}:{args.legacy_password}"
        f"@{args.legacy_host}:{args.legacy_port}/{args.legacy_db}"
    )


def build_minio_client(config: dict[str, str]) -> Minio:
    endpoint = config["oss_endpoint"]
    base_url = config.get("oss_base_url", "")
    if base_url.startswith("http://"):
        secure = False
    elif base_url.startswith("https://"):
        secure = True
    else:
        secure = endpoint.startswith("https://")
    host = endpoint.replace("http://", "").replace("https://", "")
    return Minio(
        host,
        access_key=config["oss_access_key"],
        secret_key=config["oss_secret_key"],
        secure=secure,
    )


async def fetch_legacy_categories(conn: asyncpg.Connection) -> list[LegacyCategory]:
    rows = await conn.fetch(
        """
        SELECT id, name, icon, description, COALESCE(sort_order, 0) AS sort_order
        FROM public.contract_categories
        ORDER BY id
        """
    )
    return [LegacyCategory(**dict(row)) for row in rows]


async def fetch_legacy_templates(conn: asyncpg.Connection) -> list[LegacyTemplate]:
    rows = await conn.fetch(
        """
        SELECT
            t.id,
            t.template_code,
            t.title,
            t.category_id,
            t.description,
            t.file_path,
            t.file_format,
            t.is_featured,
            t.created_at,
            t.updated_at,
            t.pdf_file_path,
            c.name AS category_name
        FROM public.contract_templates t
        LEFT JOIN public.contract_categories c ON c.id = t.category_id
        ORDER BY t.id
        """
    )
    return [LegacyTemplate(**dict(row)) for row in rows]


def resolve_docx_path(template: LegacyTemplate, object_keys: set[str]) -> str:
    file_path = (template.file_path or "").strip()
    if not file_path:
        raise ValueError(f"template {template.id} missing file_path")
    if file_path in object_keys:
        pdf_path = (template.pdf_file_path or "").strip()
        if pdf_path and pdf_path in object_keys:
            expected_docx = str(Path(pdf_path).with_suffix(".docx"))
            if expected_docx in object_keys:
                current_name = Path(file_path).name
                expected_name = Path(expected_docx).name
                if current_name != expected_name:
                    return expected_docx
        return file_path

    pdf_path = (template.pdf_file_path or "").strip()
    if pdf_path:
        expected_docx = str(Path(pdf_path).with_suffix(".docx"))
        if expected_docx in object_keys:
            return expected_docx

    raise FileNotFoundError(f"template {template.id} docx not found: {file_path}")


def resolve_pdf_path(template: LegacyTemplate, object_keys: set[str]) -> str:
    pdf_path = (template.pdf_file_path or "").strip()
    if not pdf_path:
        raise ValueError(f"template {template.id} missing pdf_file_path")
    if pdf_path in object_keys:
        return pdf_path
    raise FileNotFoundError(f"template {template.id} pdf not found: {pdf_path}")


def build_new_object_keys(template: LegacyTemplate, docx_path: str, pdf_path: str) -> tuple[str, str]:
    docx_key = OssPathUtils.BuildContractTemplateKey(
        CategoryName=template.category_name,
        TemplateCode=template.template_code,
        FileRole="source",
        FileName=Path(docx_path).name,
    )
    pdf_key = OssPathUtils.BuildContractTemplateKey(
        CategoryName=template.category_name,
        TemplateCode=template.template_code,
        FileRole="preview",
        FileName=Path(pdf_path).name,
    )
    return docx_key, pdf_key


def copy_object_bytes(
    client: Minio,
    *,
    source_bucket: str,
    source_key: str,
    target_bucket: str,
    target_key: str,
) -> None:
    response = client.get_object(source_bucket, source_key)
    try:
        payload = response.read()
    finally:
        response.close()
        response.release_conn()

    client.put_object(
        target_bucket,
        target_key,
        data=BytesIO(payload),
        length=len(payload),
    )


def ensure_bucket(client: Minio, bucket: str) -> None:
    if not client.bucket_exists(bucket):
        client.make_bucket(bucket)


async def reset_target_tables(conn: asyncpg.Connection) -> None:
    await conn.execute("TRUNCATE TABLE public.contract_templates RESTART IDENTITY CASCADE")
    await conn.execute("TRUNCATE TABLE public.contract_categories RESTART IDENTITY CASCADE")


async def insert_categories(conn: asyncpg.Connection, categories: list[LegacyCategory]) -> None:
    for category in categories:
        await conn.execute(
            """
            INSERT INTO public.contract_categories (id, name, icon, description, sort_order)
            VALUES ($1, $2, $3, $4, $5)
            """,
            category.id,
            category.name,
            category.icon,
            category.description,
            category.sort_order,
        )
    await conn.execute(
        """
        SELECT setval(
            pg_get_serial_sequence('public.contract_categories', 'id'),
            COALESCE((SELECT MAX(id) FROM public.contract_categories), 1),
            TRUE
        )
        """
    )


async def insert_templates(
    conn: asyncpg.Connection,
    templates: list[LegacyTemplate],
    template_paths: dict[int, tuple[str, str]],
) -> None:
    for template in templates:
        file_path, pdf_file_path = template_paths[template.id]
        await conn.execute(
            """
            INSERT INTO public.contract_templates (
                id,
                template_code,
                title,
                category_id,
                description,
                file_path,
                file_format,
                is_featured,
                created_at,
                updated_at,
                pdf_file_path
            )
            VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
            """,
            template.id,
            template.template_code,
            template.title,
            template.category_id,
            template.description,
            file_path,
            (template.file_format or "docx").lower(),
            bool(template.is_featured),
            template.created_at,
            template.updated_at,
            pdf_file_path,
        )
    await conn.execute(
        """
        SELECT setval(
            pg_get_serial_sequence('public.contract_templates', 'id'),
            COALESCE((SELECT MAX(id) FROM public.contract_templates), 1),
            TRUE
        )
        """
    )


async def main() -> None:
    parser = argparse.ArgumentParser(description="Migrate legacy contract templates.")
    parser.add_argument("--legacy-host", default="nas.7bm.co")
    parser.add_argument("--legacy-port", type=int, default=54302)
    parser.add_argument("--legacy-db", default="docauditai")
    parser.add_argument("--legacy-user", default="root")
    parser.add_argument("--legacy-password", default="postgresql.2025.qwe")
    parser.add_argument("--apply", action="store_true", help="Apply migration to OSS and target DB.")
    args = parser.parse_args()

    config = load_target_config()
    legacy_dsn = build_legacy_dsn(args)
    target_dsn = config["target_dsn"]
    target_bucket = config["oss_bucket"]
    minio_client = build_minio_client(config)

    legacy_conn = await asyncpg.connect(legacy_dsn)
    target_conn = await asyncpg.connect(target_dsn)
    try:
        ensure_bucket(minio_client, target_bucket)
        categories = await fetch_legacy_categories(legacy_conn)
        templates = await fetch_legacy_templates(legacy_conn)
        object_keys = {
            obj.object_name
            for obj in minio_client.list_objects(OLD_BUCKET, prefix="contract-template/", recursive=True)
        }

        template_paths: dict[int, tuple[str, str]] = {}
        for template in templates:
            docx_path = resolve_docx_path(template, object_keys)
            pdf_path = resolve_pdf_path(template, object_keys)
            template_paths[template.id] = build_new_object_keys(template, docx_path, pdf_path)

        print(f"legacy categories: {len(categories)}")
        print(f"legacy templates: {len(templates)}")
        for template in templates:
            old_docx = resolve_docx_path(template, object_keys)
            old_pdf = resolve_pdf_path(template, object_keys)
            new_docx, new_pdf = template_paths[template.id]
            print(
                f"[{template.id}] {template.template_code} | "
                f"{old_docx} -> {new_docx} | {old_pdf} -> {new_pdf}"
            )

        if not args.apply:
            print("dry-run complete; rerun with --apply to execute migration")
            return

        if args.apply:
            found_correction = False
            for template in templates:
                old_docx = resolve_docx_path(template, object_keys)
                old_pdf = resolve_pdf_path(template, object_keys)
                new_docx, new_pdf = template_paths[template.id]
                if old_docx != (template.file_path or "").strip():
                    print(
                        f"corrected docx path for template {template.id}: "
                        f"{template.file_path} -> {old_docx}"
                    )
                    found_correction = True
                copy_object_bytes(
                    minio_client,
                    source_bucket=OLD_BUCKET,
                    source_key=old_docx,
                    target_bucket=target_bucket,
                    target_key=new_docx,
                )
                copy_object_bytes(
                    minio_client,
                    source_bucket=OLD_BUCKET,
                    source_key=old_pdf,
                    target_bucket=target_bucket,
                    target_key=new_pdf,
                )
            if not found_correction:
                print("no legacy path corrections required")

            async with target_conn.transaction():
                await reset_target_tables(target_conn)
                await insert_categories(target_conn, categories)
                await insert_templates(target_conn, templates, template_paths)

            print("migration applied successfully")
    finally:
        await legacy_conn.close()
        await target_conn.close()


if __name__ == "__main__":
    asyncio.run(main())