"""DMS commands — file upload, delete, restore via Command pattern."""

from __future__ import annotations

import hashlib
import logging
import os
import uuid
from typing import Any

import redis.asyncio as aioredis
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.commands.base import BaseCommand, CommandResult
from app.core.outbox import enqueue_outbox_event
from app.core.storage import get_storage_backend

logger = logging.getLogger(__name__)

CHUNK_SIZE = 1024 * 1024  # 1MB


def _sanitize_filename(filename: str) -> str:
    """Sanitize a filename for safe use in Content-Disposition headers."""
    import re
    safe = os.path.basename(filename.replace("\\", "/"))
    safe = re.sub(r"[^a-zA-Z0-9.\-_\u00c0-\u017f\u4e00-\u9fff ]", "_", safe)
    safe = re.sub(r"\.{2,}", "_", safe)
    safe = re.sub(r" {2,}", " ", safe)
    safe = safe.lstrip(".").strip()
    if len(safe) > 200:
        name, ext = safe.rsplit(".", 1) if "." in safe[:200] else (safe[:200], "")
        safe = name[:200] + ("." + ext if ext else "")
    return safe or "file"


class UploadFileCommand(BaseCommand):
    """Upload a file to DMS with chunked streaming and SHA-256 hashing."""

    permission = "dms:write"

    def __init__(self, file_content: bytes, filename: str, mime_type: str, folder_id: str | None = None):
        self.file_content = file_content
        self.filename = _sanitize_filename(filename)
        self.mime_type = mime_type
        self.folder_id = folder_id

    async def run(self, db: AsyncSession, redis: aioredis.Redis, current_user: dict[str, Any]) -> CommandResult:
        from app.plugins.builtins.dms.models import File as DmsFile
        from app.plugins.builtins.dms.models import Folder

        tenant_id = self._tenant_id(current_user)
        user_id = self._user_id(current_user)

        # Validate folder if specified
        fid = None
        if self.folder_id:
            try:
                fid = uuid.UUID(self.folder_id)
            except ValueError:
                return CommandResult.fail("Invalid folder_id")
            folder_result = await db.execute(
                select(Folder).where(Folder.id == fid, Folder.tenant_id == tenant_id, Folder.deleted_at.is_(None))
            )
            if folder_result.scalar_one_or_none() is None:
                return CommandResult.fail("Folder not found")

        # Calculate SHA-256
        sha256 = hashlib.sha256()
        sha256.update(self.file_content)
        content_hash = sha256.hexdigest()
        file_size = len(self.file_content)

        # Create file record
        file_id = uuid.uuid4()
        storage_path = f"{tenant_id}/{file_id}"

        # Save file
        storage = get_storage_backend()
        await storage.save(storage_path, self.file_content)

        dms_file = DmsFile(
            id=file_id,
            tenant_id=tenant_id,
            name=self.filename,
            folder_id=fid,
            uploaded_by=user_id,
            mime_type=self.mime_type,
            size_bytes=file_size,
            storage_path=storage_path,
            content_hash=content_hash,
        )
        db.add(dms_file)
        await db.flush()

        # Enqueue outbox event
        await enqueue_outbox_event(db, tenant_id, "dms.file.uploaded", {
            "file_id": str(file_id),
            "name": self.filename,
            "size_bytes": file_size,
            "content_hash": content_hash,
        })

        return CommandResult.ok({
            "id": str(file_id),
            "name": self.filename,
            "size_bytes": file_size,
            "content_hash": content_hash,
            "mime_type": self.mime_type,
        })

    async def audit(self, db: AsyncSession, current_user: dict[str, Any]) -> None:
        from app.core.audit import log_audit
        await log_audit(
            db, self._tenant_id(current_user), self._user_id(current_user),
            action="dms.file.upload", entity_type="dms_file",
            changes={"name": self.filename, "size": len(self.file_content)},
        )


class DeleteFileCommand(BaseCommand):
    """Soft-delete a DMS file."""

    permission = "dms:delete"

    def __init__(self, file_id: str):
        self.file_id = file_id

    async def run(self, db: AsyncSession, redis: aioredis.Redis, current_user: dict[str, Any]) -> CommandResult:
        from datetime import UTC, datetime

        from app.plugins.builtins.dms.models import File as DmsFile

        tenant_id = self._tenant_id(current_user)
        try:
            fid = uuid.UUID(self.file_id)
        except ValueError:
            return CommandResult.fail("Invalid file_id")

        result = await db.execute(
            select(DmsFile).where(DmsFile.id == fid, DmsFile.tenant_id == tenant_id, DmsFile.deleted_at.is_(None))
        )
        dms_file = result.scalar_one_or_none()
        if dms_file is None:
            return CommandResult.fail("File not found")

        dms_file.deleted_at = datetime.now(UTC)
        await db.flush()

        await enqueue_outbox_event(db, tenant_id, "dms.file.deleted", {"file_id": self.file_id})

        return CommandResult.ok({"id": self.file_id, "deleted": True})

    async def audit(self, db: AsyncSession, current_user: dict[str, Any]) -> None:
        from app.core.audit import log_audit
        await log_audit(
            db, self._tenant_id(current_user), self._user_id(current_user),
            action="dms.file.delete", entity_type="dms_file",
            changes={"file_id": self.file_id},
        )