package services

import (
	"errors"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"platform/pkg/env"
	"platform/pkg/u"
	"platform/web/core"
	m "platform/web/models"
	q "platform/web/queries"
	"strings"
	"time"

	"github.com/google/uuid"
	"gorm.io/gen/field"
	"gorm.io/gorm"
)

var Article = &articleService{}

type articleService struct{}

var articleUploadMimeExt = map[string]string{
	"image/gif":  ".gif",
	"image/jpeg": ".jpg",
	"image/png":  ".png",
	"image/webp": ".webp",
}

type ArticleUploadResult struct {
	URL          string `json:"url"`
	Path         string `json:"path"`
	OriginalName string `json:"original_name"`
	Size         int64  `json:"size"`
	MimeType     string `json:"mime_type"`
}

func (s *articleService) UploadImage(fileHeader *multipart.FileHeader, baseURL string) (*ArticleUploadResult, error) {
	if fileHeader == nil {
		return nil, core.NewBizErr("缺少上传文件")
	}
	if fileHeader.Size > int64(env.ArticleUploadMaxBytes) {
		return nil, core.NewBizErr(fmt.Sprintf("图片大小不能超过 %s", formatUploadSizeLimit(env.ArticleUploadMaxBytes)))
	}

	mimeType, ext, err := detectArticleImage(fileHeader)
	if err != nil {
		return nil, err
	}

	now := time.Now()
	year := now.Format("2006")
	month := now.Format("01")
	fileName := uuid.NewString() + ext
	relativePath := path.Join("/uploads", "article", year, month, fileName)
	targetDir := filepath.Join(env.UploadDir, "article", year, month)
	finalPath := filepath.Join(targetDir, fileName)

	if err := os.MkdirAll(targetDir, 0o755); err != nil {
		return nil, core.NewServErr("创建上传目录失败", err)
	}

	src, err := fileHeader.Open()
	if err != nil {
		return nil, core.NewServErr("打开上传文件失败", err)
	}
	defer src.Close()

	tmp, err := os.CreateTemp(targetDir, "upload-*"+ext)
	if err != nil {
		return nil, core.NewServErr("创建临时文件失败", err)
	}

	tmpPath := tmp.Name()
	finished := false
	defer func() {
		if !finished {
			_ = tmp.Close()
			_ = os.Remove(tmpPath)
		}
	}()

	limitedReader := &io.LimitedReader{R: src, N: int64(env.ArticleUploadMaxBytes) + 1}
	written, err := io.Copy(tmp, limitedReader)
	if err != nil {
		return nil, core.NewServErr("保存上传文件失败", err)
	}
	if written > int64(env.ArticleUploadMaxBytes) {
		return nil, core.NewBizErr(fmt.Sprintf("图片大小不能超过 %s", formatUploadSizeLimit(env.ArticleUploadMaxBytes)))
	}
	if err := tmp.Close(); err != nil {
		return nil, core.NewServErr("关闭临时文件失败", err)
	}
	if err := os.Rename(tmpPath, finalPath); err != nil {
		return nil, core.NewServErr("保存上传文件失败", err)
	}
	finished = true

	cleanBaseURL := strings.TrimRight(baseURL, "/")
	url := relativePath
	if cleanBaseURL != "" {
		url = cleanBaseURL + relativePath
	}

	return &ArticleUploadResult{
		URL:          url,
		Path:         relativePath,
		OriginalName: filepath.Base(fileHeader.Filename),
		Size:         written,
		MimeType:     mimeType,
	}, nil
}

func detectArticleImage(fileHeader *multipart.FileHeader) (string, string, error) {
	file, err := fileHeader.Open()
	if err != nil {
		return "", "", core.NewServErr("打开上传文件失败", err)
	}
	defer file.Close()

	buf := make([]byte, 512)
	n, err := io.ReadFull(file, buf)
	if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
		return "", "", core.NewServErr("读取上传文件失败", err)
	}

	mimeType := http.DetectContentType(buf[:n])
	ext, ok := articleUploadMimeExt[mimeType]
	if !ok {
		return "", "", core.NewBizErr("仅支持 JPG、PNG、WEBP、GIF 图片")
	}
	return mimeType, ext, nil
}

func formatUploadSizeLimit(bytes int) string {
	if bytes%(1024*1024) == 0 {
		return fmt.Sprintf("%d MB", bytes/(1024*1024))
	}
	if bytes%1024 == 0 {
		return fmt.Sprintf("%d KB", bytes/1024)
	}
	return fmt.Sprintf("%d bytes", bytes)
}

func (s *articleService) Page(req *PageArticleReq) (result []*m.Article, count int64, err error) {
	do := q.Article.Where()
	if req.Keyword != nil && *req.Keyword != "" {
		do = do.Where(q.Article.Title.Like("%" + *req.Keyword + "%"))
	}
	if req.GroupID != nil {
		do = do.Where(q.Article.GroupID.Eq(*req.GroupID))
	}
	if req.Status != nil {
		do = do.Where(q.Article.Status.Eq(int(*req.Status)))
	}

	return q.Article.
		Preload(q.Article.Group).
		Where(do).
		Omit(q.Article.Content).
		Order(q.Article.Sort, q.Article.CreatedAt).
		FindByPage(req.GetOffset(), req.GetLimit())
}

type PageArticleReq struct {
	core.PageReq
	Keyword *string          `json:"keyword,omitempty"`
	GroupID *int32           `json:"group_id,omitempty"`
	Status  *m.ArticleStatus `json:"status,omitempty"`
}

func (s *articleService) GetByAdmin(id int32) (*m.Article, error) {
	article, err := q.Article.
		Preload(q.Article.Group).
		Where(q.Article.ID.Eq(id)).
		Take()
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, core.NewBizErr("文档不存在")
	}
	if err != nil {
		return nil, err
	}
	return article, nil
}

func (s *articleService) Create(data CreateArticleData) error {
	if err := s.ensureGroupExists(data.GroupID); err != nil {
		return err
	}

	return q.Article.Create(&m.Article{
		GroupID: data.GroupID,
		Title:   data.Title,
		Content: data.Content,
		Sort:    u.Else(data.Sort, 0),
		Status:  u.Else(data.Status, m.ArticleStatusEnabled),
	})
}

type CreateArticleData struct {
	GroupID int32            `json:"group_id" validate:"required"`
	Title   string           `json:"title" validate:"required"`
	Content *string          `json:"content"`
	Sort    *int32           `json:"sort"`
	Status  *m.ArticleStatus `json:"status"`
}

func (s *articleService) Update(data UpdateArticleData) error {
	if data.GroupID != nil {
		if err := s.ensureGroupExists(*data.GroupID); err != nil {
			return err
		}
	}

	do := make([]field.AssignExpr, 0)
	if data.GroupID != nil {
		do = append(do, q.Article.GroupID.Value(*data.GroupID))
	}
	if data.Title != nil {
		do = append(do, q.Article.Title.Value(*data.Title))
	}
	if data.Content != nil {
		do = append(do, q.Article.Content.Value(*data.Content))
	}
	if data.Sort != nil {
		do = append(do, q.Article.Sort.Value(*data.Sort))
	}
	if data.Status != nil {
		do = append(do, q.Article.Status.Value(int(*data.Status)))
	}
	if len(do) == 0 {
		return nil
	}

	r, err := q.Article.Where(q.Article.ID.Eq(data.ID)).UpdateSimple(do...)
	if err != nil {
		return err
	}
	if r.RowsAffected == 0 {
		return core.NewBizErr("文档状态已过期")
	}
	return nil
}

type UpdateArticleData struct {
	ID      int32            `json:"id" validate:"required"`
	GroupID *int32           `json:"group_id"`
	Title   *string          `json:"title"`
	Content *string          `json:"content"`
	Sort    *int32           `json:"sort"`
	Status  *m.ArticleStatus `json:"status"`
}

func (s *articleService) Delete(id int32) error {
	r, err := q.Article.Where(q.Article.ID.Eq(id)).UpdateColumn(q.Article.DeletedAt, time.Now())
	if err != nil {
		return err
	}
	if r.RowsAffected == 0 {
		return core.NewBizErr("文档状态已过期")
	}
	return nil
}

func (s *articleService) Nav() ([]*ArticleNavGroup, error) {
	groups, err := q.ArticleGroup.
		Where(q.ArticleGroup.Status.Eq(int(m.ArticleGroupStatusEnabled))).
		Order(q.ArticleGroup.Sort, q.ArticleGroup.CreatedAt).
		Find()
	if err != nil {
		return nil, err
	}
	if len(groups) == 0 {
		return []*ArticleNavGroup{}, nil
	}

	groupIDs := make([]int32, 0, len(groups))
	result := make([]*ArticleNavGroup, 0, len(groups))
	groupMap := make(map[int32]*ArticleNavGroup, len(groups))
	for _, group := range groups {
		groupIDs = append(groupIDs, group.ID)
		item := &ArticleNavGroup{
			ID:       group.ID,
			Name:     group.Name,
			Code:     group.Code,
			Articles: []*ArticleNavArticle{},
		}
		result = append(result, item)
		groupMap[group.ID] = item
	}

	articles, err := q.Article.
		Where(
			q.Article.GroupID.In(groupIDs...),
			q.Article.Status.Eq(int(m.ArticleStatusEnabled)),
		).
		Omit(q.Article.Content).
		Order(q.Article.Sort, q.Article.CreatedAt).
		Find()
	if err != nil {
		return nil, err
	}

	for _, article := range articles {
		group := groupMap[article.GroupID]
		if group == nil {
			continue
		}
		group.Articles = append(group.Articles, &ArticleNavArticle{
			ID:        article.ID,
			Title:     article.Title,
			UpdatedAt: article.UpdatedAt,
		})
	}

	return result, nil
}

type ArticleNavGroup struct {
	ID       int32                `json:"id"`
	Name     string               `json:"name"`
	Code     string               `json:"code"`
	Articles []*ArticleNavArticle `json:"articles"`
}

type ArticleNavArticle struct {
	ID        int32     `json:"id"`
	Title     string    `json:"title"`
	UpdatedAt time.Time `json:"updated_at"`
}

func (s *articleService) GetPublic(id int32) (*ArticlePublicDetail, error) {
	article, err := q.Article.
		Preload(q.Article.Group).
		Where(
			q.Article.ID.Eq(id),
			q.Article.Status.Eq(int(m.ArticleStatusEnabled)),
		).
		Take()
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return nil, core.NewBizErr("文档不存在")
	}
	if err != nil {
		return nil, err
	}
	if article.Group == nil || article.Group.Status != m.ArticleGroupStatusEnabled {
		return nil, core.NewBizErr("文档不存在")
	}

	return &ArticlePublicDetail{
		ID:        article.ID,
		Title:     article.Title,
		Content:   article.Content,
		UpdatedAt: article.UpdatedAt,
		Group: &ArticlePublicGroup{
			ID:   article.Group.ID,
			Name: article.Group.Name,
			Code: article.Group.Code,
		},
	}, nil
}

type ArticlePublicDetail struct {
	ID        int32               `json:"id"`
	Title     string              `json:"title"`
	Content   *string             `json:"content,omitempty"`
	UpdatedAt time.Time           `json:"updated_at"`
	Group     *ArticlePublicGroup `json:"group"`
}

type ArticlePublicGroup struct {
	ID   int32  `json:"id"`
	Name string `json:"name"`
	Code string `json:"code"`
}

func (s *articleService) ensureGroupExists(groupID int32) error {
	_, err := q.ArticleGroup.Where(q.ArticleGroup.ID.Eq(groupID)).Take()
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return core.NewBizErr("文档分组不存在")
	}
	return err
}