package handlers

import (
	"fmt"
	"io"
	"net/http"
	"path/filepath"

	apperrors "veza-backend-api/internal/errors"
	"veza-backend-api/internal/services"
	chatws "veza-backend-api/internal/websocket/chat"

	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
	"go.uber.org/zap"
)

const chatAttachmentMaxSize = 50 * 1024 * 1024 // 50MB

// ChatAttachmentHandler handles chat file uploads (v0.9.7)
type ChatAttachmentHandler struct {
	s3Service    *services.S3StorageService
	permissions  *chatws.PermissionService
	validator    UploadValidatorInterface
	logger       *zap.Logger
	urlExpirySec int64
}

// NewChatAttachmentHandler creates a new ChatAttachmentHandler
func NewChatAttachmentHandler(
	s3Service *services.S3StorageService,
	permissions *chatws.PermissionService,
	validator UploadValidatorInterface,
	logger *zap.Logger,
) *ChatAttachmentHandler {
	if logger == nil {
		logger = zap.NewNop()
	}
	return &ChatAttachmentHandler{
		s3Service:    s3Service,
		permissions:  permissions,
		validator:    validator,
		logger:       logger,
		urlExpirySec: 86400, // 24h
	}
}

// UploadChatAttachment handles POST /api/v1/chat/rooms/:roomId/attachments
// Accepts: audio (mp3, wav, ogg), image (jpg, png), PDF. Max 50MB.
func (h *ChatAttachmentHandler) UploadChatAttachment(c *gin.Context) {
	userID, ok := GetUserIDUUID(c)
	if !ok {
		return
	}

	roomID, err := uuid.Parse(c.Param("roomId"))
	if err != nil {
		RespondWithAppError(c, apperrors.NewValidationError("Invalid room ID"))
		return
	}

	if !h.permissions.CanRead(c.Request.Context(), userID, roomID) {
		RespondWithAppError(c, apperrors.NewForbiddenError("Not allowed to access this conversation"))
		return
	}

	fileHeader, err := c.FormFile("file")
	if err != nil {
		RespondWithAppError(c, apperrors.NewValidationError("No file provided"))
		return
	}

	if fileHeader.Size > chatAttachmentMaxSize {
		RespondWithAppError(c, apperrors.NewValidationError("File too large. Max 50MB"))
		return
	}

	if fileHeader.Size == 0 {
		RespondWithAppError(c, apperrors.NewValidationError("Empty file"))
		return
	}

	fileType := h.validator.GetFileTypeFromPath(fileHeader.Filename)
	if fileType == "unknown" {
		RespondWithAppError(c, apperrors.NewValidationError("Unsupported file type. Allowed: mp3, wav, ogg, jpg, png, pdf"))
		return
	}

	validationResult, err := h.validator.ValidateFile(c.Request.Context(), fileHeader, fileType)
	if err != nil {
		h.logger.Warn("Chat attachment validation failed", zap.Error(err), zap.String("filename", fileHeader.Filename))
		RespondWithAppError(c, apperrors.NewValidationError("File validation failed: "+err.Error()))
		return
	}

	if !validationResult.Valid {
		RespondWithAppError(c, apperrors.NewValidationError(validationResult.Error))
		return
	}

	if validationResult.Quarantined {
		RespondWithAppError(c, apperrors.NewForbiddenError("File rejected: virus detected"))
		return
	}

	file, err := fileHeader.Open()
	if err != nil {
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Failed to read file", err))
		return
	}
	defer file.Close()

	data, err := io.ReadAll(file)
	if err != nil {
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Failed to read file", err))
		return
	}

	ext := filepath.Ext(fileHeader.Filename)
	if ext == "" {
		ext = ".bin"
	}
	key := fmt.Sprintf("chat/%s/%s/%s%s", roomID, userID, uuid.New().String(), ext)

	_, err = h.s3Service.UploadFile(c.Request.Context(), data, key, fileHeader.Header.Get("Content-Type"))
	if err != nil {
		h.logger.Error("Failed to upload chat attachment", zap.Error(err), zap.String("key", key))
		RespondWithAppError(c, apperrors.NewInternalErrorWrap("Failed to upload file", err))
		return
	}

	// Return presigned URL for download (24h)
	signedURL, err := h.s3Service.GetPresignedURL(c.Request.Context(), key)
	if err != nil {
		// Fallback to public URL if presigned fails (e.g. public bucket)
		signedURL = h.s3Service.GetPublicURL(key)
	}

	RespondSuccess(c, http.StatusCreated, gin.H{
		"url":      signedURL,
		"file_id":  uuid.New().String(),
		"file_name": fileHeader.Filename,
		"file_size": fileHeader.Size,
		"file_type": fileType,
	})
}