package httpapi

import (
	"context"
	"crypto/md5"
	"encoding/hex"
	"io"
	"net/http"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"github.com/sundynix/pets-be/internal/model"
)

func (a *API) fileExists(id string) bool {
	if !validID(id) {
		return false
	}
	var count int64
	a.db.Model(&model.File{}).Where("id = ?", id).Count(&count)
	return count == 1
}

const maxUploadSize = 10 << 20

func (a *API) uploadFile(c *gin.Context) {
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, maxUploadSize+1024)
	header, err := c.FormFile("file")
	if err != nil || header.Size <= 0 || header.Size > maxUploadSize {
		fail(c, http.StatusBadRequest, "请选择不超过 10 MB 的图片")
		return
	}
	reader, err := header.Open()
	if err != nil {
		fail(c, http.StatusBadRequest, "读取图片失败")
		return
	}
	defer reader.Close()
	signature := make([]byte, 512)
	n, _ := io.ReadFull(reader, signature)
	contentType := http.DetectContentType(signature[:n])
	extensions := map[string]string{"image/jpeg": ".jpg", "image/png": ".png", "image/webp": ".webp"}
	ext, allowed := extensions[contentType]
	if !allowed {
		fail(c, http.StatusBadRequest, "仅支持 JPG、PNG、WebP 图片")
		return
	}
	if _, err := reader.Seek(0, io.SeekStart); err != nil {
		fail(c, http.StatusBadRequest, "读取图片失败")
		return
	}
	hasher := md5.New()
	if _, err := io.Copy(hasher, reader); err != nil {
		fail(c, http.StatusBadRequest, "读取图片失败")
		return
	}
	if _, err := reader.Seek(0, io.SeekStart); err != nil {
		fail(c, http.StatusBadRequest, "读取图片失败")
		return
	}
	digest := hex.EncodeToString(hasher.Sum(nil))
	var existing model.File
	if a.db.Where("md5 = ?", digest).First(&existing).Error == nil {
		if existing.Size != header.Size {
			fail(c, http.StatusConflict, "文件校验冲突")
			return
		}
		ok(c, a.fileView(existing))
		return
	}
	key := "files/" + digest[:2] + "/" + digest + ext
	ctx, cancel := context.WithTimeout(c.Request.Context(), 45*time.Second)
	defer cancel()
	if err := a.storage.Put(ctx, key, reader, header.Size, contentType); err != nil {
		fail(c, http.StatusBadGateway, "上传对象存储失败")
		return
	}
	file := model.File{
		Bucket: a.storage.Bucket(), ObjectKey: key, MD5: digest, URL: a.storage.PublicURL(key),
		Name: strings.TrimSpace(header.Filename), ContentType: contentType,
		Size: header.Size,
	}
	if err := a.db.Create(&file).Error; err != nil {
		if a.db.Where("md5 = ?", digest).First(&existing).Error == nil && existing.Size == header.Size {
			ok(c, a.fileView(existing))
			return
		}
		fail(c, http.StatusInternalServerError, "保存文件信息失败")
		return
	}
	created(c, a.fileView(file))
}

func (a *API) getFile(c *gin.Context) {
	if !validID(c.Param("id")) {
		fail(c, http.StatusBadRequest, "文件 ID 无效")
		return
	}
	var file model.File
	if err := a.db.Where("id = ?", c.Param("id")).First(&file).Error; err != nil {
		fail(c, http.StatusNotFound, "文件不存在")
		return
	}
	ok(c, a.fileView(file))
}

func (a *API) fileView(file model.File) gin.H {
	return gin.H{"id": file.ID, "name": file.Name, "content_type": file.ContentType,
		"size": file.Size, "md5": file.MD5, "url": file.URL}
}

func (a *API) fileURL(id *string) string {
	if id == nil || !validID(*id) {
		return ""
	}
	var file model.File
	if a.db.Select("url").First(&file, "id = ?", *id).Error != nil {
		return ""
	}
	return file.URL
}

func (a *API) userView(user model.User) gin.H {
	return gin.H{"id": user.ID, "nickname": user.Nickname, "avatar_file_id": user.AvatarFileID,
		"avatar_url": a.fileURL(user.AvatarFileID), "created_at": user.CreatedAt}
}

func (a *API) petView(pet model.Pet) gin.H {
	var birthDate string
	if pet.BirthDate != nil {
		birthDate = pet.BirthDate.Format("2006-01-02")
	}
	return gin.H{"id": pet.ID, "name": pet.Name, "species": pet.Species, "breed": pet.Breed,
		"gender": pet.Gender, "birth_date": birthDate, "weight_kg": pet.WeightKg,
		"avatar_file_id": pet.AvatarFileID, "avatar_url": a.fileURL(pet.AvatarFileID),
		"coat": pet.Coat, "allergies": pet.Allergies, "care_notes": pet.CareNotes,
		"created_at": pet.CreatedAt}
}