package file

import (
	"ResendIt/internal/api/middleware"
	"ResendIt/internal/config"
	"ResendIt/internal/logger"
	"ResendIt/internal/notify"
	"ResendIt/internal/util"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"time"

	"github.com/gin-gonic/gin"
)

type Handler struct {
	service       *Service
	configService ConfigService
}

// ConfigService is the small interface we need from the config package.
// Keeping it as an interface avoids import cycles and keeps file.Handler easy to test.
type ConfigService interface {
	GetIntDefault(key string, def int) int
	GetInt64Default(key string, def int64) int64
	GetStringDefault(key string, def string) string
}

func NewHandler(s *Service, cfg ConfigService) *Handler {
	return &Handler{service: s, configService: cfg}
}

func (h *Handler) Upload(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "file_upload").
		Logger()

	err := c.Request.ParseMultipartForm(0)
	if err != nil {
		log.Warn().Str("reason", "parse_error").Err(err).Msg("Upload failed")
		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
		return
	}

	file, err := c.FormFile("file")
	if err != nil {
		log.Warn().Str("reason", "missing_file").Msg("Upload failed")
		c.JSON(http.StatusBadRequest, gin.H{"error": "missing file"})
		return
	}

	maxSize := h.configService.GetInt64Default(config.KeyUploadMaxFileSizeBytes, config.DefaultUploadMaxFileSizeBytes)
	if file.Size > maxSize {
		log.Warn().
			Str("reason", "file_too_large").
			Int64("file_size", file.Size).
			Int64("max_size", maxSize).
			Msg("Upload rejected")
		c.JSON(http.StatusRequestEntityTooLarge, gin.H{"error": "file too large"})
		return
	}

	f, err := file.Open()
	if err != nil {
		log.Error().Err(err).Msg("Failed to open uploaded file")
		c.JSON(http.StatusInternalServerError, gin.H{"error": "cannot open file"})
		return
	}
	defer f.Close()

	once := c.PostForm("once") == "true"

	durationStr := c.PostForm("duration")
	hours, err := strconv.Atoi(durationStr)
	if err != nil || hours <= 0 {
		hours = 24 // default
	}
	maxHours := h.configService.GetIntDefault(config.KeyUploadMaxHours, config.DefaultUploadMaxHours)
	if hours > maxHours {
		hours = maxHours
	}

	duration := time.Duration(hours) * time.Hour

	record, err := h.service.UploadFile(
		file.Filename,
		f,
		once,
		duration,
	)
	if err != nil {
		log.Error().Err(err).Msg("Upload failed")
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	log.Info().
		Str("file_id", record.ID).
		Str("filename", record.Filename).
		Int64("file_size", record.Size).
		Bool("once", once).
		Msg("File uploaded successfully")

	enabled := h.configService.GetIntDefault(config.KeyUseNtfy, config.DefaultUseNtfy)
	if enabled == 1 {
		ntfyURL := h.configService.GetStringDefault(config.KeyNtfyUrl, "")
		topic := h.configService.GetStringDefault(config.KeyNtfyTopic, config.DefaultNtfyTopic)

		go func() {
			title := "ReSendit: new upload"
			msg := fmt.Sprintf("%s (%s)\nID: %s", record.Filename, util.HumanSize(record.Size), record.ID)
			clickUrl := fmt.Sprintf("f/%s", record.ViewID)
			if err := notify.Publish(ntfyURL, topic, title, msg, clickUrl); err != nil {
				logger.Log.Warn().Err(err).Str("type", "ntfy").Msg("ntfy publish failed")
			}
		}()
	}

	c.JSON(http.StatusOK, gin.H{
		"id":          record.ID,
		"deletion_id": record.DeletionID,
		"filename":    record.Filename,
		"size":        record.Size,
		"expires_at":  record.ExpiresAt,
		"view_key":    record.ViewID,
	})
}

func (h *Handler) View(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "file_view").
		Logger()

	id := c.Param("id")

	record, err := h.service.DownloadFile(id)
	if err != nil {
		log.Warn().Str("file_id", id).Err(err).Msg("File view failed - not found")
		c.HTML(http.StatusOK, "error.html", nil)
		return
	}

	log.Info().Str("file_id", id).Str("filename", record.Filename).Msg("File viewed")

	name := util.SafeFilename(record.Filename)
	c.Header("Content-Disposition", fmt.Sprintf(`inline; filename="%s"`, name))
	c.Header("X-Content-Type-Options", "nosniff")
	c.File(record.Path)
}

func isXSSRisk(filename string) bool {
	ext := filepath.Ext(filename)
	switch ext {
	case ".html", ".htm", ".js", ".css", ".svg":
		return true
	default:
		return false
	}
}

func (h *Handler) Download(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "file_download").
		Logger()

	id := c.Param("id")

	record, err := h.service.DownloadFile(id)
	if err != nil {
		log.Warn().Str("file_id", id).Err(err).Msg("File download failed - not found")
		c.HTML(http.StatusOK, "error.html", nil)
		return
	}

	log.Info().Str("file_id", id).Str("filename", record.Filename).Int64("size", record.Size).Msg("File downloaded")

	name := util.SafeFilename(record.Filename)
	c.Header("Content-Disposition", fmt.Sprintf(`inline; filename="%s"`, name))
	c.Header("X-Content-Type-Options", "nosniff")
	c.File(record.Path)
}

func (h *Handler) Delete(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "file_delete").
		Logger()

	id := c.Param("del_id")

	record, err := h.service.DeleteFileByDeletionID(id)
	if err != nil {
		log.Warn().Str("deletion_id", id).Err(err).Msg("File delete failed")
		c.HTML(http.StatusOK, "error.html", nil)
		return
	}

	log.Info().
		Str("file_id", record.ID).
		Str("filename", record.Filename).
		Msg("File deleted")

	c.HTML(http.StatusOK, "deleted.html", nil)
}

func (h *Handler) AdminList(c *gin.Context) {
	records, err := h.service.repo.GetAll()
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, records)
}

func (h *Handler) AdminGet(c *gin.Context) {
	id := c.Param("id")

	record, err := h.service.repo.GetByID(id)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "file not found"})
		return
	}

	c.Header("Content-Disposition", fmt.Sprintf(`inline; filename="%s"`, util.SafeFilename(record.Filename)))
	c.Header("X-Content-Type-Options", "nosniff")

	c.File(record.Path)
}

func (h *Handler) AdminDelete(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "admin_file_delete").
		Logger()

	id := c.Param("id")

	record, err := h.service.DeleteFileByID(id)
	if err != nil {
		log.Warn().Str("file_id", id).Err(err).Msg("Admin file delete failed")
		c.JSON(http.StatusNotFound, gin.H{"error": "file not found"})
		return
	}

	log.Info().Str("file_id", record.ID).Str("filename", record.Filename).Msg("Admin deleted file")

	c.Redirect(301, "/admin")
}

func (h *Handler) AdminForceDelete(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "admin_file_force_delete").
		Logger()

	id := c.Param("id")

	_, err := h.service.GetFileByID(id)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "file not found"})
		return
	}

	if _, err := h.service.ForceDelete(id); err != nil {
		log.Error().Err(err).Msg("Admin force delete failed")
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	log.Info().Str("file_id", id).Msg("Admin force deleted file")

	c.Redirect(301, "/admin")
}

func (h *Handler) AdminReinstate(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "admin_file_reinstate").
		Logger()

	id := c.Param("id")

	_, err := h.service.GetFileByID(id)
	if err != nil {
		c.JSON(http.StatusNotFound, gin.H{"error": "file not found"})
		return
	}

	if _, err := h.service.ReinstateFile(id); err != nil {
		log.Error().Err(err).Msg("Admin reinstate failed")
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	log.Info().Str("file_id", id).Msg("Admin reinstated file")

	c.Redirect(301, "/admin")
}

func (h *Handler) Import(c *gin.Context) {
	var records []ImportFileRecord

	if err := c.ShouldBindJSON(&records); err != nil {
		c.JSON(400, gin.H{"error": "invalid JSON"})
		return
	}

	if err := h.service.ImportFiles(records); err != nil {
		c.JSON(500, gin.H{"error": err.Error()})
		return
	}

	c.JSON(200, gin.H{
		"imported": len(records),
	})
}

func (h *Handler) Export(c *gin.Context) {
	records, err := h.service.GetAllFiles()
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, records)
}

// Chunked stuff
func (h *Handler) UploadInit(c *gin.Context) {
	var req struct {
		Filename    string `json:"filename"`
		TotalChunks int    `json:"totalChunks"`
		Size        int64  `json:"size"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(400, gin.H{"error": "invalid request"})
		return
	}

	fileID := util.RandomString(32)

	// create temp folder
	path := filepath.Join("tmp", fileID)
	if err := os.MkdirAll(path, os.ModePerm); err != nil {
		c.JSON(500, gin.H{"error": "failed to create temp dir"})
		return
	}

	c.JSON(200, gin.H{
		"fileId": fileID,
	})
}

func (h *Handler) UploadChunk(c *gin.Context) {
	fileID := c.GetHeader("fileId")
	chunkIndex := c.GetHeader("chunkIndex")

	if fileID == "" || chunkIndex == "" {
		c.JSON(400, gin.H{"error": "missing headers"})
		return
	}

	idx, err := strconv.Atoi(chunkIndex)
	if err != nil {
		c.JSON(400, gin.H{"error": "invalid chunkIndex"})
		return
	}

	file, err := c.FormFile("chunk")
	if err != nil {
		c.JSON(400, gin.H{"error": "missing chunk"})
		return
	}

	src, err := file.Open()
	if err != nil {
		c.JSON(500, gin.H{"error": "cannot open chunk"})
		return
	}
	defer src.Close()

	chunkPath := filepath.Join("tmp", fileID, fmt.Sprintf("chunk_%d", idx))

	dst, err := os.Create(chunkPath)
	if err != nil {
		c.JSON(500, gin.H{"error": "cannot save chunk"})
		return
	}
	defer dst.Close()

	if _, err := io.Copy(dst, src); err != nil {
		c.JSON(500, gin.H{"error": "write failed"})
		return
	}

	c.JSON(200, gin.H{"status": "ok"})
}

func (h *Handler) UploadComplete(c *gin.Context) {
	log := middleware.StructuredLog(c).With().
		Str("event", "chunked_upload_complete").
		Logger()

	var req struct {
		FileID      string `json:"fileId"`
		Filename    string `json:"filename"`
		TotalChunks int    `json:"totalChunks"`
	}

	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(400, gin.H{"error": "invalid request"})
		return
	}

	tmpDir := filepath.Join("tmp", req.FileID)

	// create pipe to stream into your existing service
	pr, pw := io.Pipe()

	go func() {
		defer pw.Close()

		for i := 0; i < req.TotalChunks; i++ {
			chunkPath := filepath.Join(tmpDir, fmt.Sprintf("chunk_%d", i))

			f, err := os.Open(chunkPath)
			if err != nil {
				pw.CloseWithError(err)
				return
			}

			if _, err := io.Copy(pw, f); err != nil {
				f.Close()
				pw.CloseWithError(err)
				return
			}

			f.Close()
		}
	}()

	record, err := h.service.UploadFile(
		req.Filename,
		pr,
		false,
		24*time.Hour,
	)
	if err != nil {
		log.Error().Err(err).Msg("Chunked upload failed")
		c.JSON(500, gin.H{"error": err.Error()})
		return
	}

	_ = os.RemoveAll(tmpDir)

	log.Info().
		Str("file_id", record.ID).
		Str("filename", record.Filename).
		Int("chunks", req.TotalChunks).
		Msg("Chunked upload completed")

	c.JSON(200, gin.H{
		"id":       record.ID,
		"view_key": record.ViewID,
	})
}

func (h *Handler) UploadStatus(c *gin.Context) {
	fileID := c.Param("fileId")

	dir := filepath.Join("tmp", fileID)

	files, err := os.ReadDir(dir)
	if err != nil {
		c.JSON(404, gin.H{"error": "not found"})
		return
	}

	var uploaded []int

	for _, f := range files {
		var idx int
		_, err := fmt.Sscanf(f.Name(), "chunk_%d", &idx)
		if err == nil {
			uploaded = append(uploaded, idx)
		}
	}

	c.JSON(200, gin.H{
		"uploadedChunks": uploaded,
	})
}