#!/usr/bin/env python3
"""
CLI entry point: fetch mods that were previously missing but have since been
added to the file server, then link them.

Flow:
  1. Load missing_report.json
  2. Re-check server index for newly available mods
  3. Download newly available mods to their correct group folder
  4. Update missing_report.json (remove the ones now downloaded)
  5. Run link_group for each affected group

Usage:
    python sync_missing.py
"""

import json
import sys

from tqdm import tqdm

from arma_modlist_tools.compat import fix_console_encoding
from arma_modlist_tools.config import load_config
from arma_modlist_tools.fetcher import (
    build_server_index, find_mod_folder,
    list_mod_files, download_file, make_session,
)
from arma_modlist_tools.linker import link_group
from arma_modlist_tools.reporter import save_missing_report

fix_console_encoding()


def _fmt_bytes(n: int) -> str:
    for unit in ("B", "KB", "MB", "GB"):
        if n < 1024:
            return f"{n:.1f} {unit}"
        n /= 1024
    return f"{n:.1f} TB"


def main() -> None:
    cfg = load_config()

    # ---- Load missing report ----
    if not cfg.missing_report.exists():
        print(f"\nERROR: {cfg.missing_report} not found.")
        print("Run report_missing.py or fetch_mods.py first.\n")
        sys.exit(1)

    report = json.loads(cfg.missing_report.read_text(encoding="utf-8"))
    previously_missing = report["missing_mods"]

    if not previously_missing:
        print("\nNo mods in missing report — nothing to sync.\n")
        sys.exit(0)

    print(f"\nLoading missing report: {len(previously_missing)} mods previously missing")

    # ---- Re-check server index ----
    print("Re-checking server index...")
    index = build_server_index(cfg.server_url, cfg.server_auth)
    print(f"  {len(index['by_steam_id'])} mods indexed\n")

    session = make_session(cfg.server_auth)

    # ---- Resolve which are now available ----
    now_available: list[tuple[dict, str]] = []  # (mod, folder_url)
    still_missing: list[dict] = []

    for mod in previously_missing:
        url = find_mod_folder(mod, index)
        if url:
            now_available.append((mod, url))
        else:
            still_missing.append(mod)

    print(f"  Newly available: {len(now_available)} mods")
    print(f"  Still missing  : {len(still_missing)} mods\n")

    if not now_available:
        print("No new mods available on server yet.\n")
        sys.exit(0)

    # ---- Download newly available mods ----
    affected_groups: set[str] = set()
    total_bytes = 0

    with tqdm(total=len(now_available), unit="mod", desc="Downloading", position=0, dynamic_ncols=True) as mod_bar:
        for mod, folder_url in now_available:
            group       = mod["group"]
            folder_name = folder_url.rstrip("/").split("/")[-1]
            dest_path   = cfg.downloads / group / folder_name

            tqdm.write(f"  [+] {folder_name:<48}  -> downloads/{group}/")

            files = list_mod_files(folder_url, session)
            mod_bytes = 0

            for rel, file_url, size in files:
                dest_file = dest_path / rel
                if dest_file.exists():
                    continue
                with tqdm(
                    total=size if size else None,
                    unit="B", unit_scale=True, unit_divisor=1024,
                    desc=f"  {rel[-45:]:45s}",
                    position=1, leave=False, dynamic_ncols=True,
                ) as file_bar:
                    n = download_file(
                        file_url, dest_file, session,
                        on_chunk=lambda b: file_bar.update(b),
                    )
                mod_bytes += n

            tqdm.write(f"     Done  {_fmt_bytes(mod_bytes)}")
            total_bytes += mod_bytes
            affected_groups.add(group)
            mod_bar.update(1)

    print(f"\n  Downloaded: {len(now_available)} mods  {_fmt_bytes(total_bytes)}")

    # ---- Update missing report ----
    report["missing_mods"] = still_missing
    report["missing"]      = len(still_missing)
    report["on_server"]    = report["total_mods"] - len(still_missing)
    save_missing_report(report, cfg.missing_report)
    print(f"  Missing report updated: {len(still_missing)} still missing\n")

    # ---- Link newly downloaded mods ----
    if not cfg.arma_dir.exists():
        print(f"  NOTE: Arma dir not found ({cfg.arma_dir}) — skipping link step.")
        print("  Run link_mods.py manually when ready.\n")
        sys.exit(0)

    print("Linking newly added mods...")
    for group in sorted(affected_groups):
        group_dir = cfg.downloads / group
        result    = link_group(group_dir, cfg.arma_dir)
        print(f"  {group:<30}  "
              f"{result['linked']} new linked, "
              f"{result['already_linked']} already linked"
              + (f", {result['failed']} failed" if result["failed"] else ""))

    print("\nDone.\n")


if __name__ == "__main__":
    main()