from __future__ import annotations

import json
import shutil
from pathlib import Path
from typing import Iterable


def _load_json(path: Path) -> dict:
    try:
        raw = path.read_text(encoding="utf-8")
    except OSError:
        return {}
    try:
        data = json.loads(raw)
    except json.JSONDecodeError:
        return {}
    return data if isinstance(data, dict) else {}


def _from_build(build_dir: Path, relative_path: object) -> Path | None:
    if not isinstance(relative_path, str) or not relative_path.strip():
        return None
    candidate = build_dir / relative_path
    if candidate.exists() and candidate.is_file():
        return candidate
    return None


def _collect_from_flasher_args(build_dir: Path) -> dict[str, Path]:
    result: dict[str, Path] = {}
    data = _load_json(build_dir / "flasher_args.json")

    flash_files = data.get("flash_files")
    if isinstance(flash_files, dict):
        for rel in flash_files.values():
            path = _from_build(build_dir, rel)
            if path is not None:
                result[path.name] = path

    for key in ("bootloader", "app", "partition-table"):
        section = data.get(key)
        if not isinstance(section, dict):
            continue
        path = _from_build(build_dir, section.get("file"))
        if path is not None:
            result[path.name] = path

    return result


def _find_in_build_tree(build_dir: Path, name: str) -> Path | None:
    direct = build_dir / name
    if direct.exists() and direct.is_file():
        return direct
    for path in build_dir.glob(f"**/{name}"):
        if path.is_file():
            return path
    return None


def sync_bins_from_idf_build(
    bin_dir: Path,
    required_bins: Iterable[str],
    build_dir: Path,
) -> list[tuple[Path, Path]]:
    if not build_dir.exists() or not build_dir.is_dir():
        return []

    build_map = _collect_from_flasher_args(build_dir)
    copied: list[tuple[Path, Path]] = []
    seen: set[str] = set()
    for raw_name in required_bins:
        name = str(raw_name).strip()
        if not name or name in seen:
            continue
        seen.add(name)

        target = bin_dir / name
        if target.exists():
            continue

        source = build_map.get(name)
        if source is None:
            source = _find_in_build_tree(build_dir, name)
        if source is None:
            continue

        target.parent.mkdir(parents=True, exist_ok=True)
        shutil.copy2(source, target)
        copied.append((source, target))
    return copied