package photosapi

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"mime"
	"net/http"
	"path/filepath"
	"strings"
	"time"

	"github.com/dsoprea/go-exif/v3"
	"github.com/gin-gonic/gin"
	"github.com/jackc/pgconn"
	"gorm.io/gorm"
)

// Error
var (
	// Store
	ErrStoreBadChecksum        = errors.New("checksum should be sha1 in hex format")
	ErrStoreBadChunkSize       = errors.New("part file size should be 1MB max")
	ErrStoreMissingChunks      = errors.New("part checksum missing")
	ErrStoreWrongChecksum      = errors.New("wrong checksum")
	ErrStoreMismatchChecksum   = errors.New("part files doesn't match the original checksum")
	ErrStoreAlreadyExists      = errors.New("original file already exists")
	ErrStoreChunkAlreadyExists = errors.New("chunk file already exists")
	ErrStoreMissingName        = errors.New("name required")
)

// Model
type File struct {
	ID        uint32       `gorm:"primary_key" json:"id"`
	Name      string       `gorm:"not null" json:"name"`
	Checksum  string       `gorm:"unique;size:44;not null"`
	Size      uint64       `gorm:"not null"`
	Author    *Account     `gorm:"constraint:OnDelete:SET NULL,OnUpdate:CASCADE" json:"author"`
	AuthorId  *uint32      `json:"-"`
	Chunks    []*FileChunk `gorm:"constraint:OnDelete:CASCADE,OnUpdate:CASCADE"`
	CreatedAt time.Time    `json:"created_at"`
	UpdatedAt time.Time    `json:"updated_at"`
}

type FileChunk struct {
	FileId    uint32
	File      *File `gorm:"constraint:OnDelete:CASCADE,OnUpdate:CASCADE"`
	Part      uint32
	Checksum  string    `gorm:"unique;size:44;not null"`
	CreatedAt time.Time `json:"created_at"`
	UpdatedAt time.Time `json:"updated_at"`
}

// Service
var CHUNK_SIZE int64 = 4 << 20

type FileRequest struct {
	Name     string   `json:"name"`
	Checksum string   `json:"checksum"`
	Chunks   []string `json:"chunks"`
}

func (s *Service) FileCreate(c *gin.Context) {
	file := &FileRequest{}
	if err := c.ShouldBindJSON(file); err != nil {
		s.Error(c, http.StatusInternalServerError, err)
		return
	}

	if len(file.Name) < 1 {
		s.Error(c, http.StatusBadRequest, ErrStoreMissingName)
		return
	}

	if len(file.Checksum) != 40 {
		s.Error(c, http.StatusBadRequest, ErrStoreBadChecksum)
		return
	}
	if len(file.Chunks) == 0 {
		s.Error(c, http.StatusBadRequest, ErrStoreMissingChunks)
		return
	}

	for _, chunk := range file.Chunks {
		if len(chunk) != 40 {
			s.Error(c, http.StatusBadRequest, ErrStoreBadChecksum)
			return
		}
	}

	r, rs, err := s.Store.Combine(file.Chunks)
	if err != nil {
		if strings.HasPrefix(err.Error(), "chunk") && strings.HasSuffix(err.Error(), "doesn't exists") {
			s.Error(c, http.StatusBadRequest, err)
		} else {
			s.Error(c, http.StatusInternalServerError, err)
		}
		return
	}

	if r != file.Checksum {
		s.Error(c, http.StatusExpectationFailed, ErrStoreMismatchChecksum)
		return
	}

	sess := s.CurrentSession(c)

	f := &File{
		Name:     file.Name,
		Checksum: file.Checksum,
		Size:     rs,
		AuthorId: &sess.AccountId,
	}

	err = s.DB.Transaction(func(tx *gorm.DB) error {
		if err := tx.Create(f).Error; err != nil {
			return err
		}
		for i, chunk := range file.Chunks {
			fc := &FileChunk{
				FileId:   f.ID,
				Part:     uint32(i + 1),
				Checksum: chunk,
			}
			if err := tx.Create(fc).Error; err != nil {
				return err
			}
		}
		return nil
	})

	if nerr, ok := err.(*pgconn.PgError); ok {
		if nerr.Code == "23505" && nerr.Detail == fmt.Sprintf("Key (checksum)=(%s) already exists.", file.Checksum) {
			err = nil
		}
	}

	if err != nil {
		s.Error(c, http.StatusInternalServerError, err)
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"status":   "success",
		"sum":      file.Checksum,
		"nbChunks": len(file.Chunks),
		"size":     rs,
	})
}

func (s *Service) FileCreateChunk(c *gin.Context) {
	if c.Request.ContentLength > CHUNK_SIZE {
		s.Error(c, http.StatusBadRequest, ErrStoreBadChunkSize)
		return
	}

	b := bytes.NewBuffer([]byte{})
	io.Copy(b, c.Request.Body)
	c.Request.Body.Close()

	sess := s.CurrentSession(c)

	chunk := s.Store.NewChunk(b.Bytes())
	if err := chunk.Save(sess.Account.Login); err != nil {
		if errors.Is(err, ErrStoreChunkAlreadyExists) {
			c.JSON(http.StatusOK, gin.H{
				"status":   "success",
				"checksum": chunk.Sum,
			})
		} else {
			s.Error(c, http.StatusBadRequest, err)
		}
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"status":   "success",
		"checksum": chunk.Sum,
	})
}

func (s *Service) FileChunkExists(c *gin.Context) {
	checksum := c.Param("checksum")
	if len(checksum) != 40 {
		s.Error(c, http.StatusBadRequest, ErrStoreBadChecksum)
		return
	}

	if s.Store.Chunk(checksum).FileExists() {
		c.Status(http.StatusOK)
	} else {
		c.Status(http.StatusNotFound)
	}
}

func (s *Service) FileExists(c *gin.Context) {
	checksum := c.Param("checksum")
	if len(checksum) != 40 {
		s.Error(c, http.StatusBadRequest, ErrStoreBadChecksum)
		return
	}

	var fileExists int64
	if err := s.DB.Model(&File{}).Where("checksum = ?", checksum).Count(&fileExists).Error; err != nil {
		s.Error(c, http.StatusInternalServerError, err)
		return
	}

	if fileExists > 0 {
		c.Status(http.StatusOK)
	} else {
		c.Status(http.StatusNotFound)
	}
}

func (s *Service) FileGet(c *gin.Context) {
	checksum := c.Param("checksum")
	if len(checksum) != 40 {
		s.Error(c, http.StatusBadRequest, ErrStoreBadChecksum)
		return
	}
	if checksum == c.GetHeader("If-None-Match") {
		c.Status(http.StatusNotModified)
		return
	}

	f := &File{}
	if err := s.DB.Debug().Preload("Chunks").Where("checksum = ?", checksum).First(&f).Error; err != nil {
		s.Error(c, http.StatusBadRequest, err)
		return
	}

	chunks := make([]string, len(f.Chunks))
	for _, fc := range f.Chunks {
		chunks[fc.Part-1] = fc.Checksum
	}

	reader, err := s.Store.NewStoreReader(chunks)
	if err != nil {
		s.Error(c, http.StatusInternalServerError, err)
		return
	}
	defer reader.Close()

	c.DataFromReader(
		http.StatusOK,
		reader.Size,
		mime.TypeByExtension(filepath.Ext(f.Name)),
		reader,
		map[string]string{
			"Content-Disposition": fmt.Sprintf("inline; filename=\"%s\"", f.Name),
			"ETag":                f.Checksum,
		},
	)
}

func (s *Service) FileAnalyze(c *gin.Context) {
	checksum := c.Param("checksum")
	if len(checksum) != 40 {
		s.Error(c, http.StatusBadRequest, ErrStoreBadChecksum)
		return
	}

	f := &File{}
	if err := s.DB.Debug().Preload("Chunks").Where("checksum = ?", checksum).First(&f).Error; err != nil {
		s.Error(c, http.StatusBadRequest, err)
		return
	}

	chunks := make([]string, len(f.Chunks))
	for _, fc := range f.Chunks {
		chunks[fc.Part-1] = fc.Checksum
	}

	reader, err := s.Store.NewStoreReader(chunks)
	if err != nil {
		s.Error(c, http.StatusInternalServerError, err)
		return
	}
	defer reader.Close()

	rawExif, err := exif.SearchAndExtractExifWithReader(reader)
	if err != nil {
		s.Error(c, http.StatusInternalServerError, err)
		return
	}
	entries, _, err := exif.GetFlatExifDataUniversalSearch(rawExif, nil, true)
	if err != nil {
		s.Error(c, http.StatusInternalServerError, err)
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"exif": entries,
	})
}

func (s *Service) FileInit() {
	file := s.Gin.Group("/file")
	file.Use(s.RequireSession)
	file.POST("", s.FileCreate)
	file.HEAD("/:checksum", s.FileExists)
	file.GET("/:checksum", s.FileGet)
	file.POST("/chunk", s.FileCreateChunk)
	file.HEAD("/chunk/:checksum", s.FileChunkExists)
	file.GET("/analyze/:checksum", s.FileAnalyze)
}