#!/usr/bin/env python3
"""Download and archive documents from the Kyrgyz Republic Ministry of Justice."""

from __future__ import annotations

import argparse
import base64
import hashlib
import json
import logging
import os
import sqlite3
import sys
import tempfile
import time
import urllib.error
import urllib.parse
import urllib.request
from dataclasses import dataclass
from datetime import datetime, timezone
from pathlib import Path
from typing import Callable, Iterable

APP_VERSION = "0.7.1"
API_BASE_URL = "https://cbd.minjust.gov.kg/api/v1/OpenData/"
LANGUAGES = {"Rus": "ru", "Kyr": "ky"}
IMAGE_LANGUAGES = {"Russian": "ru", "Kyrgyz": "ky"}
LOGGER = logging.getLogger(__name__)


class CbdClient:
    def __init__(
        self,
        requests_per_second: float = 1,
        timeout: int = 60,
        retries: int = 5,
    ) -> None:
        if requests_per_second <= 0:
            raise ValueError("requests_per_second must be greater than zero")
        if timeout <= 0 or retries <= 0:
            raise ValueError("timeout and retries must be greater than zero")
        # ponytail: per-process limit; add a distributed lock before multiple workers.
        self.interval = 1 / requests_per_second
        self.timeout = timeout
        self.retries = retries
        self.last_request = 0.0
        self.total_documents = 0

    def request_json(self, method: str, parameters: Iterable[tuple[str, object]] = ()):
        query = urllib.parse.urlencode(list(parameters), doseq=True)
        extension = "" if method == "CheckAvailable" else ".json"
        url = f"{API_BASE_URL}{method}{extension}" + (f"?{query}" if query else "")
        for attempt in range(self.retries):
            retry_delay = 2**attempt
            wait = self.interval - (time.monotonic() - self.last_request)
            if wait > 0:
                time.sleep(wait)
            request = urllib.request.Request(
                url,
                headers={
                    "Accept": "application/json",
                    "User-Agent": f"Akyldash/{APP_VERSION} (+https://cbd.minjust.gov.kg)",
                },
            )
            try:
                self.last_request = time.monotonic()
                with urllib.request.urlopen(request, timeout=self.timeout) as response:
                    body = response.read()
                    return json.loads(body) if body else None
            except urllib.error.HTTPError as error:
                if error.code != 429 and error.code < 500:
                    raise
                if error.code == 429:
                    try:
                        retry_delay = max(
                            retry_delay, float(error.headers.get("Retry-After", 0))
                        )
                    except ValueError:
                        pass
            except (TimeoutError, urllib.error.URLError):
                pass
            if attempt + 1 < self.retries:
                time.sleep(retry_delay)
        raise RuntimeError(f"Ministry of Justice API request failed: {url}")

    def check_available(self) -> None:
        self.request_json("CheckAvailable")

    def document_codes(self, limit: int | None = None, page_size: int = 1000):
        def query_page(page_number: int):
            return self.request_json(
                "GetDocumentListByQuery",
                (
                    ("Property", "Code"),
                    ("PageSize", page_size),
                    ("PageNumber", page_number),
                ),
            )

        first = query_page(1)
        yielded = 0
        page = first
        page_number = 1
        self.total_documents = min(first["TotalCount"], limit or first["TotalCount"])
        while True:
            for document in page["Documents"]:
                yield document["Code"]
                yielded += 1
                if limit is not None and yielded >= limit:
                    return
            if yielded >= page["TotalCount"]:
                return
            page_number += 1
            try:
                page = self.request_json(
                    "GetDocumentListById",
                    (
                        ("DocumentListId", first["Id"]),
                        ("Property", "Code"),
                        ("PageSize", page_size),
                        ("PageNumber", page_number),
                    ),
                )
            except (urllib.error.HTTPError, RuntimeError) as error:
                if isinstance(error, urllib.error.HTTPError) and error.code != 404:
                    raise
                first = page = query_page(page_number)
                self.total_documents = min(
                    first["TotalCount"], limit or first["TotalCount"]
                )

    def document(self, code: int) -> dict:
        return self.request_json(
            "GetDocument",
            (
                ("Code", code),
                ("Editions.Select", "all"),
                ("Editions.Data", "all"),
                ("Editions.Images.Select", "all"),
                ("Editions.Images.Data", "all"),
            ),
        )


@dataclass(frozen=True)
class SyncResult:
    discovered: int = 0
    downloaded: int = 0
    skipped: int = 0
    failed: int = 0


def format_duration(seconds: float) -> str:
    seconds = max(0, round(seconds))
    hours, seconds = divmod(seconds, 3600)
    minutes, seconds = divmod(seconds, 60)
    return f"{hours:02d}:{minutes:02d}:{seconds:02d}"


def progress_line(
    result: SyncResult, total: int, elapsed: float, width: int = 24
) -> str:
    processed = result.discovered
    fraction = processed / total if total else 0
    filled = min(width, round(width * fraction))
    rate = processed / elapsed if elapsed > 0 else 0
    eta = (total - processed) / rate if rate else 0
    return (
        f"[{'#' * filled}{'-' * (width - filled)}] {fraction:6.2%} "
        f"{processed}/{total} downloaded={result.downloaded} "
        f"skipped={result.skipped} failed={result.failed} "
        f"rate={rate:.2f}/s ETA={format_duration(eta)}"
    )


def terminal_progress() -> Callable[[SyncResult, int], None]:
    started = time.monotonic()

    def update(result: SyncResult, total: int) -> None:
        line = progress_line(result, total, time.monotonic() - started)
        print(
            f"\r{line}",
            end="\n" if result.discovered >= total else "",
            file=sys.stderr,
            flush=True,
        )

    return update


def connect_manifest(path: Path) -> sqlite3.Connection:
    path.parent.mkdir(parents=True, exist_ok=True)
    connection = sqlite3.connect(path)
    connection.execute(
        """
        CREATE TABLE IF NOT EXISTS documents (
            code INTEGER PRIMARY KEY,
            source_sha256 TEXT NOT NULL,
            fetched_at TEXT NOT NULL
        )
        """
    )
    connection.execute(
        """
        CREATE TABLE IF NOT EXISTS errors (
            code INTEGER PRIMARY KEY,
            message TEXT NOT NULL,
            failed_at TEXT NOT NULL
        )
        """
    )
    return connection


def atomic_write(path: Path, content: bytes) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    with tempfile.NamedTemporaryFile(dir=path.parent, delete=False) as temporary:
        temporary.write(content)
        temporary_path = Path(temporary.name)
    os.replace(temporary_path, path)


def json_bytes(value: object) -> bytes:
    return (json.dumps(value, ensure_ascii=False, indent=2) + "\n").encode()


def archive_document(root: Path, document: dict) -> str:
    code = int(document["Code"])
    source = json.dumps(document, ensure_ascii=False, sort_keys=True).encode()
    source_sha256 = hashlib.sha256(source).hexdigest()
    directory = root / "documents" / str(code)
    editions = document.get("Editions") or []
    metadata = {key: value for key, value in document.items() if key != "Editions"}
    atomic_write(directory / "metadata.json", json_bytes(metadata))

    for edition in editions:
        edition_directory = directory / "editions" / str(int(edition["Code"]))
        edition_metadata = {key: value for key, value in edition.items() if key != "Data"}
        edition_metadata["Images"] = [
            {key: value for key, value in image.items() if key != "Data"}
            for image in edition.get("Images") or []
        ]
        atomic_write(edition_directory / "metadata.json", json_bytes(edition_metadata))

        for source_language, filename in LANGUAGES.items():
            html = (edition.get("Data") or {}).get(source_language)
            if html:
                atomic_write(edition_directory / f"{filename}.html", html.encode())

        for image in edition.get("Images") or []:
            if not image.get("Data"):
                continue
            language = IMAGE_LANGUAGES.get(image.get("Lang"), "unknown")
            filename = Path(str(image.get("Name") or "image").replace("\\", "/")).name
            if filename in {"", ".", ".."}:
                raise ValueError(f"Invalid image filename in document {code}")
            atomic_write(
                edition_directory / "images" / language / filename,
                base64.b64decode(image["Data"], validate=True),
            )
    return source_sha256


def sync_archive(
    output: Path,
    client: CbdClient | None = None,
    limit: int | None = None,
    refresh: bool = False,
    progress: Callable[[SyncResult, int], None] | None = None,
) -> SyncResult:
    client = client or CbdClient()
    output.mkdir(parents=True, exist_ok=True)
    connection = connect_manifest(output / "manifest.sqlite3")
    known = {row[0] for row in connection.execute("SELECT code FROM documents")}
    discovered = downloaded = skipped = failed = 0

    client.check_available()
    for code in client.document_codes(limit):
        discovered += 1
        # ponytail: refresh scans all documents; use sitemap lastmod when scheduled
        # update checks become frequent enough for the extra mapping logic to pay off.
        if code in known and not refresh:
            skipped += 1
            if progress:
                progress(
                    SyncResult(discovered, downloaded, skipped, failed),
                    client.total_documents,
                )
            continue
        try:
            document = client.document(code)
            checksum = archive_document(output, document)
            fetched_at = datetime.now(timezone.utc).isoformat()
            with connection:
                connection.execute(
                    """
                    INSERT INTO documents (code, source_sha256, fetched_at)
                    VALUES (?, ?, ?)
                    ON CONFLICT(code) DO UPDATE SET
                        source_sha256 = excluded.source_sha256,
                        fetched_at = excluded.fetched_at
                    """,
                    (int(document["Code"]), checksum, fetched_at),
                )
                connection.execute("DELETE FROM errors WHERE code = ?", (code,))
            downloaded += 1
        except Exception as error:  # Continue the long-running archive after one bad record.
            with connection:
                connection.execute(
                    """
                    INSERT INTO errors (code, message, failed_at) VALUES (?, ?, ?)
                    ON CONFLICT(code) DO UPDATE SET
                        message = excluded.message,
                        failed_at = excluded.failed_at
                    """,
                    (code, str(error), datetime.now(timezone.utc).isoformat()),
                )
            failed += 1
        if progress:
            progress(
                SyncResult(discovered, downloaded, skipped, failed),
                client.total_documents,
            )
        if not progress and discovered % 100 == 0:
            LOGGER.info(
                "discovered=%s downloaded=%s skipped=%s failed=%s",
                discovered,
                downloaded,
                skipped,
                failed,
            )
    connection.close()
    return SyncResult(discovered, downloaded, skipped, failed)


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--output", type=Path, default=Path("data/minjust-cbd"))
    parser.add_argument("--limit", type=int, help="download only the first N documents")
    parser.add_argument("--refresh", action="store_true", help="redownload known documents")
    parser.add_argument("--requests-per-second", type=float, default=1)
    parser.add_argument("--timeout", type=int, default=60)
    parser.add_argument("--retries", type=int, default=5)
    parser.add_argument("--version", action="version", version=APP_VERSION)
    return parser.parse_args()


def main() -> int:
    arguments = parse_args()
    if arguments.limit is not None and arguments.limit <= 0:
        raise SystemExit("--limit must be greater than zero")
    logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s")
    result = sync_archive(
        arguments.output,
        CbdClient(
            requests_per_second=arguments.requests_per_second,
            timeout=arguments.timeout,
            retries=arguments.retries,
        ),
        arguments.limit,
        arguments.refresh,
        terminal_progress() if sys.stderr.isatty() else None,
    )
    print(
        f"discovered={result.discovered} downloaded={result.downloaded} "
        f"skipped={result.skipped} failed={result.failed}\n"
        f"Akyldash Backend v{APP_VERSION} · Frontend — not created"
    )
    return int(result.failed > 0)


if __name__ == "__main__":
    raise SystemExit(main())