# processors/case_normalizer.py

import os

from core.constants import IMAGE_EXTENSIONS
from core.result import StepResult


def preview_normalize_case(work_dir: str, mode: str = "lower") -> list[tuple[str, str]]:
    """Devuelve lista de (nombre_actual, nombre_final) sin modificar nada."""
    result = []
    for root, _, files in os.walk(work_dir):
        for f in files:
            stem, ext = os.path.splitext(f)
            if not ext or ext.lower() not in IMAGE_EXTENSIONS:
                continue
            target_ext = ext.lower() if mode == "lower" else ext.upper()
            if ext != target_ext:
                result.append((f, stem + target_ext))
    return sorted(result)


def normalize_case(work_dir: str, mode: str = "lower") -> StepResult:
    """
    Renombra las extensiones de las imágenes en work_dir al case indicado.
    Solo afecta a extensiones de imagen (IMAGE_EXTENSIONS); ComicInfo.xml y
    otros ficheros no de imagen quedan intactos.
    En Linux (FS sensible al case) el rename directo es seguro.
    """
    changed = False
    details = []

    for root, _, files in os.walk(work_dir):
        for f in files:
            stem, ext = os.path.splitext(f)
            if not ext or ext.lower() not in IMAGE_EXTENSIONS:
                continue
            target_ext = ext.lower() if mode == "lower" else ext.upper()
            if ext == target_ext:
                continue
            src = os.path.join(root, f)
            dst = os.path.join(root, stem + target_ext)
            os.rename(src, dst)
            details.append(f"{f} → {stem + target_ext}")
            changed = True

    return StepResult(step="normalize_case", changed=changed, details=details)