import json
from datetime import datetime
from pathlib import Path
from typing import Any

from ..db import get_database


class ExportHandler:
    SCHEMA_VERSION = "1.0"

    def __init__(self, db_path: str | None = None):
        self.db = get_database(db_path)

    def export_all(self) -> dict[str, Any]:
        snippets = self.db.get_all_snippets_for_sync()
        collections = self.db.collection_list()
        return {
            "version": self.SCHEMA_VERSION,
            "exported_at": datetime.utcnow().isoformat(),
            "snippets": snippets,
            "collections": collections,
        }

    def export_collection(self, collection_id: int) -> dict[str, Any]:
        snippets = self.db.list_snippets(collection_id=collection_id, limit=1000)
        self.db.get_cursor()
        cursor = self.db.get_cursor().__enter__()
        cursor.execute(
            "SELECT * FROM collections WHERE id = ?", (collection_id,)
        )
        collection = dict(cursor.fetchone()) if cursor.fetchone() else None
        return {
            "version": self.SCHEMA_VERSION,
            "exported_at": datetime.utcnow().isoformat(),
            "collection": collection,
            "snippets": snippets,
        }

    def export_snippet(self, snippet_id: int) -> dict[str, Any] | None:
        snippet = self.db.get_snippet(snippet_id)
        if not snippet:
            return None
        return {
            "version": self.SCHEMA_VERSION,
            "exported_at": datetime.utcnow().isoformat(),
            "snippets": [snippet],
        }

    def write_export(self, filepath: str | Path, export_data: dict[str, Any], indent: int = 2):
        with open(filepath, "w") as f:
            json.dump(export_data, f, indent=indent)

    def import_data(self, filepath: str | Path, strategy: str = "skip") -> dict[str, Any]:
        with open(filepath) as f:
            data = json.load(f)
        if not self._validate_import_data(data):
            raise ValueError("Invalid import file format")
        snippets = data.get("snippets", [])
        collections = data.get("collections", [])
        results = {
            "imported": 0,
            "skipped": 0,
            "replaced": 0,
            "duplicates": 0,
            "errors": [],
        }
        for snippet in snippets:
            try:
                result = self._import_snippet(snippet, strategy)
                if result == "imported":
                    results["imported"] += 1
                elif result == "skipped":
                    results["skipped"] += 1
                elif result == "replaced":
                    results["replaced"] += 1
                elif result == "duplicate":
                    results["duplicates"] += 1
            except Exception as e:
                results["errors"].append({"snippet": snippet.get("title", "unknown"), "error": str(e)})
        for collection in collections:
            try:
                self._import_collection(collection)
            except Exception:
                pass
        return results

    def _import_snippet(self, snippet: dict[str, Any], strategy: str) -> str:
        snippet_id = snippet.get("id")
        existing = None
        if snippet_id:
            existing = self.db.get_snippet(snippet_id)
        if existing and strategy == "skip":
            return "skipped"
        if existing and strategy == "replace":
            self.db.upsert_snippet(snippet)
            return "replaced"
        if existing and strategy == "duplicate":
            new_snippet = dict(snippet)
            new_snippet["id"] = None
            new_snippet["title"] = f"{snippet.get('title', 'Snippet')} (imported)"
            self.db.create_snippet(
                title=new_snippet["title"],
                code=new_snippet["code"],
                description=new_snippet.get("description", ""),
                language=new_snippet.get("language", "text"),
                tags=new_snippet.get("tags", []),
                is_encrypted=bool(new_snippet.get("is_encrypted")),
            )
            return "duplicates"
        self.db.upsert_snippet(snippet)
        return "imported"

    def _import_collection(self, collection: dict[str, Any]):
        name = collection.get("name")
        if not name:
            return
        try:
            collection_id = self.db.collection_create(
                name=name,
                description=collection.get("description", ""),
            )
            snippet_ids = collection.get("snippet_ids", [])
            for snippet_id in snippet_ids:
                self.db.collection_add_snippet(collection_id, snippet_id)
        except Exception:
            pass

    def _validate_import_data(self, data: dict[str, Any]) -> bool:
        if not isinstance(data, dict):
            return False
        if "snippets" not in data and "collections" not in data:
            return False
        if "snippets" in data and not isinstance(data["snippets"], list):
            return False
        return True

    def generate_import_summary(self, results: dict[str, Any]) -> str:
        lines = ["Import Results:", f"  Imported: {results['imported']}"]
        if results["skipped"]:
            lines.append(f"  Skipped: {results['skipped']}")
        if results["replaced"]:
            lines.append(f"  Replaced: {results['replaced']}")
        if results["duplicates"]:
            lines.append(f"  Duplicates: {results['duplicates']}")
        if results["errors"]:
            lines.append(f"  Errors: {len(results['errors'])}")
            for err in results["errors"][:5]:
                lines.append(f"    - {err['snippet']}: {err['error']}")
        return "\n".join(lines)