"""backend/services/serialization.py

Persistance simple (JSON/YAML) pour les workflows.

Auteur : Dom, Alice, Kiro - 08 janvier 2026

Patch #1:
- Fournit WorkflowDatabase + WorkflowSerializer utilisés par api/workflows.py
- Stockage fichier: un workflow = un fichier <id>.json dans un répertoire

Design:
- Permissif: on conserve les champs inconnus via models.py
- Robuste: erreurs encapsulées, pas de crash au boot
"""

from __future__ import annotations

import json
import os
from dataclasses import dataclass
from typing import Any, Dict, Optional, List

import yaml  # PyYAML

from models import VisualWorkflow, generate_id, WorkflowSettings
from datetime import datetime


class SerializationError(Exception):
    """Erreur de sérialisation."""
    pass


class ValidationError(Exception):
    """Erreur de validation pour les workflows sérialisés."""

    def __init__(self, errors: List[str]):
        super().__init__(", ".join(errors))
        self.errors = errors


def create_empty_workflow(name: str, description: str, created_by: str) -> VisualWorkflow:
    """Crée un workflow vide avec les paramètres de base."""
    now = datetime.now()
    return VisualWorkflow(
        id=WorkflowSerializer.generate_workflow_id(),
        name=name,
        description=description,
        version="1.0.0",
        created_at=now,
        updated_at=now,
        created_by=created_by,
        nodes=[],
        edges=[],
        variables=[],
        settings=WorkflowSettings(),
    )


class WorkflowSerializer:
    """Sérialise/désérialise les workflows vers/depuis JSON ou YAML."""

    @staticmethod
    def generate_workflow_id() -> str:
        """Génère un identifiant unique pour un workflow."""
        return generate_id("wf")

    @staticmethod
    def serialize(workflow: VisualWorkflow, format: str = "json") -> str:
        """Sérialise un workflow vers une chaîne JSON ou YAML."""
        try:
            data = workflow.to_dict()
            fmt = (format or "json").lower()
            if fmt == "json":
                return json.dumps(data, ensure_ascii=False, indent=2)
            if fmt in ("yml", "yaml"):
                return yaml.safe_dump(data, allow_unicode=True, sort_keys=False)
            raise SerializationError(f"Format non supporté: {format}")
        except Exception as e:
            raise SerializationError(str(e)) from e

    @staticmethod
    def deserialize(raw: Any, format: str = "json") -> VisualWorkflow:
        """Désérialise un workflow depuis une chaîne JSON ou YAML."""
        try:
            fmt = (format or "json").lower()

            if isinstance(raw, (bytes, bytearray)):
                raw = raw.decode("utf-8", errors="replace")

            if isinstance(raw, str):
                if fmt == "json":
                    data = json.loads(raw)
                elif fmt in ("yml", "yaml"):
                    data = yaml.safe_load(raw)
                else:
                    raise SerializationError(f"Format non supporté: {format}")
            elif isinstance(raw, dict):
                data = raw
            else:
                raise SerializationError("Type d'entrée invalide pour la désérialisation")

            wf = VisualWorkflow.from_dict(data)
            errors = wf.validate()
            if errors:
                raise ValidationError(errors)
            return wf
        except ValidationError:
            raise
        except Exception as e:
            raise SerializationError(str(e)) from e


@dataclass
class WorkflowDatabase:
    """Stockage de workflows basé sur des fichiers."""

    root_dir: str

    def __post_init__(self) -> None:
        """Crée le répertoire de stockage s'il n'existe pas."""
        os.makedirs(self.root_dir, exist_ok=True)

    def _path(self, workflow_id: str) -> str:
        """Retourne le chemin du fichier pour un workflow donné."""
        safe_id = "".join(c for c in workflow_id if c.isalnum() or c in ("_", "-")) or workflow_id
        return os.path.join(self.root_dir, f"{safe_id}.json")

    def exists(self, workflow_id: str) -> bool:
        """Vérifie si un workflow existe."""
        return os.path.exists(self._path(workflow_id))

    def save(self, workflow: VisualWorkflow) -> None:
        """Sauvegarde un workflow sur disque."""
        try:
            payload = WorkflowSerializer.serialize(workflow, format="json")
            with open(self._path(workflow.id), "w", encoding="utf-8") as f:
                f.write(payload)
        except Exception as e:
            raise SerializationError(f"Échec de la sauvegarde du workflow: {e}") from e

    def load(self, workflow_id: str) -> Optional[VisualWorkflow]:
        """Charge un workflow depuis le disque."""
        path = self._path(workflow_id)
        if not os.path.exists(path):
            return None
        try:
            with open(path, "r", encoding="utf-8") as f:
                raw = f.read()
            return WorkflowSerializer.deserialize(raw, format="json")
        except ValidationError:
            raise
        except Exception as e:
            raise SerializationError(f"Échec du chargement du workflow '{workflow_id}': {e}") from e

    def delete(self, workflow_id: str) -> None:
        """Supprime un workflow du disque."""
        path = self._path(workflow_id)
        try:
            if os.path.exists(path):
                os.remove(path)
        except Exception as e:
            raise SerializationError(f"Échec de la suppression du workflow '{workflow_id}': {e}") from e

    def list(self) -> List[VisualWorkflow]:
        """Liste tous les workflows disponibles.

        Les fichiers invalides sont ignorés silencieusement pour éviter
        de bloquer le chargement de tous les workflows.
        """
        workflows: List[VisualWorkflow] = []
        if not os.path.isdir(self.root_dir):
            return []
        for fname in os.listdir(self.root_dir):
            if not fname.endswith(".json"):
                continue
            wf_id = fname[:-5]
            try:
                wf = self.load(wf_id)
                if wf is not None:
                    workflows.append(wf)
            except (SerializationError, ValidationError) as e:
                # Ignorer les fichiers invalides et continuer
                print(f"⚠️ Workflow ignoré '{wf_id}': {e}")
            except Exception as e:
                # Autres erreurs - les ignorer aussi pour ne pas bloquer
                print(f"⚠️ Erreur inattendue pour '{wf_id}': {e}")
        return workflows