import os
import re

from .config import make_slug


def task_image_path(image_root, task, account=None, suffix="old", ext=".jpg"):
    batch_id = _safe_component(_get(task, "batch_id"), "unknown_batch")
    slug = _account_slug(account, task)
    task_id = _safe_component(_get(task, "id"), "task")
    item_id = _safe_component(_get(task, "item_id"), "item")
    suffix = _safe_component(suffix, "image")
    ext = str(ext or ".jpg")
    if not ext.startswith("."):
        ext = "." + ext
    return os.path.abspath(
        os.path.join(
            str(image_root or "images"),
            batch_id,
            slug,
            f"{task_id}_{item_id}_{suffix}{ext}",
        )
    )


def list_task_cover_candidates(image_root, task, account=None):
    """Return generated cover candidates for one task from the image directory."""

    canonical_path = task_image_path(image_root, task, account=account, suffix="new", ext=".jpg")
    directory = os.path.dirname(canonical_path)
    prefix = os.path.splitext(os.path.basename(canonical_path))[0]
    if not os.path.isdir(directory):
        return []
    candidates = []
    for filename in os.listdir(directory):
        full_path = os.path.join(directory, filename)
        if not os.path.isfile(full_path):
            continue
        stem, ext = os.path.splitext(filename)
        if ext.lower() != ".jpg":
            continue
        if stem == prefix or stem.startswith(prefix + "_"):
            candidates.append(os.path.abspath(full_path))
    return sorted(candidates, key=lambda path: _cover_candidate_sort_key(path, prefix))


def _account_slug(account, task):
    slug = _get(account, "slug")
    if slug:
        return _safe_component(slug, "unknown_account")
    alias = _get(task, "alias") or _get(account, "alias") or _get(task, "account_name") or _get(account, "account_name")
    if alias:
        return _safe_component(make_slug(alias), "unknown_account")
    return "unknown_account"


def _cover_candidate_sort_key(path, prefix):
    filename = os.path.basename(path)
    stem, _ext = os.path.splitext(filename)
    if stem == prefix:
        return (0, 0, 0, filename)
    marker = prefix + "_"
    if stem.startswith(marker):
        suffix = stem[len(marker):]
        match = re.fullmatch(r"(\d{14})(?:_(\d+))?", suffix)
        if match:
            timestamp = int(match.group(1))
            collision = int(match.group(2) or 1)
            return (1, -timestamp, -collision, filename)
    return (2, 0, 0, filename)


def _get(obj, name, default=None):
    if obj is None:
        return default
    if isinstance(obj, dict):
        return obj.get(name, default)
    return getattr(obj, name, default)


def _safe_component(value, default):
    text = str(value or "").strip()
    if not text:
        text = str(default)
    safe = "".join(ch if ch.isalnum() or ch in "_-" else "_" for ch in text).strip("_")
    return safe or str(default)