import json
import os
import asyncio
from datetime import datetime

FICHIER_TACHES = "taches.json"
FICHIER_TACHES_TMP = "taches.json.tmp"
FICHIER_ID = "id_compteur.json"
file_lock = asyncio.Lock()

async def charger_taches():
    async with file_lock:
        if not os.path.exists(FICHIER_TACHES):
            with open(FICHIER_TACHES, "w", encoding='utf-8') as f:
                json.dump({"taches": {}}, f, indent=4)
        with open(FICHIER_TACHES, "r", encoding='utf-8') as f:
            return json.load(f)

async def sauvegarder_taches(donnees):
    async with file_lock:
        with open(FICHIER_TACHES_TMP, "w", encoding='utf-8') as f:
            json.dump(donnees, f, indent=4, ensure_ascii=False)
        os.replace(FICHIER_TACHES_TMP, FICHIER_TACHES)

async def generer_id_unique():
    async with file_lock:
        if not os.path.exists(FICHIER_ID):
            with open(FICHIER_ID, "w", encoding='utf-8') as f:
                json.dump({"dernier_id": 0}, f, indent=4)

        with open(FICHIER_ID, "r+", encoding='utf-8') as f:
            data = json.load(f)
            data["dernier_id"] += 1
            f.seek(0)
            json.dump(data, f, indent=4)
            f.truncate()
            return str(data["dernier_id"])

async def ajouter_tache(titre, description, user_id, priorite, date_echeance, auteur_id):
    data = await charger_taches()
    taches = data["taches"]
    id_tache = await generer_id_unique()

    taches[id_tache] = {
        "titre": titre,
        "description": description,
        "assigné": user_id,
        "statut": "À faire",
        "priorité": priorite,
        "échéance": date_echeance,
        "créé_par": auteur_id,
        "commentaires": []
    }

    await sauvegarder_taches(data)
    return id_tache

async def update_tache_status(id_tache, statut):
    data = await charger_taches()
    if id_tache in data["taches"]:
        data["taches"][id_tache]["statut"] = statut
        await sauvegarder_taches(data)
        return True
    return False

async def supprimer_tache(id_tache):
    data = await charger_taches()
    if id_tache in data["taches"]:
        del data["taches"][id_tache]
        await sauvegarder_taches(data)
        return True
    return False

async def lister_taches_utilisateur(user_id):
    data = await charger_taches()
    return {tid: t for tid, t in data["taches"].items() if t["assigné"] == user_id}

async def taches_proches():
    data = await charger_taches()
    proches = {}
    now = datetime.now()
    for tid, t in data["taches"].items():
        try:
            date_obj = datetime.strptime(t["échéance"], "%Y-%m-%d")
            if 0 <= (date_obj - now).days <= 2:
                proches[tid] = t
        except ValueError:
            continue
    return proches