package services

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

type PDFService struct{}

func NewPDFService() *PDFService {
	return &PDFService{}
}

type PDFInfo struct {
	Pages    int    `json:"pages"`
	Title    string `json:"title"`
	Author   string `json:"author"`
	FilePath string `json:"filePath"`
	Size     int64  `json:"size"`
}

func (s *PDFService) GetPDFInfo(filePath string) (*PDFInfo, error) {
	fileInfo, err := os.Stat(filePath)
	if err != nil {
		return nil, fmt.Errorf("获取文件信息失败: %v", err)
	}

	pages := 1
	data, err := os.ReadFile(filePath)
	if err == nil {
		content := string(data)
		pages = strings.Count(content, "/Type /Page") - strings.Count(content, "/Type /Pages")
		if pages <= 0 {
			pages = 1
		}
	}

	return &PDFInfo{
		Pages:    pages,
		Title:    filepath.Base(filePath),
		Author:   "",
		FilePath: filePath,
		Size:     fileInfo.Size(),
	}, nil
}

func (s *PDFService) CompressPDF(inputPath, outputPath string, quality string) error {
	if outputPath == "" {
		outputPath = GetOutputPath(inputPath, "_compressed")
	}

	inData, err := os.ReadFile(inputPath)
	if err != nil {
		return fmt.Errorf("读取PDF文件失败: %v", err)
	}

	err = os.WriteFile(outputPath, inData, 0644)
	if err != nil {
		return fmt.Errorf("保存PDF文件失败: %v", err)
	}

	return nil
}

func (s *PDFService) SplitPDF(inputPath, outputDir string, pages string) ([]string, error) {
	if outputDir == "" {
		outputDir = filepath.Dir(inputPath)
	}

	baseName := GetBaseName(inputPath)
	outputPath := filepath.Join(outputDir, baseName+"_split.pdf")

	inData, err := os.ReadFile(inputPath)
	if err != nil {
		return nil, fmt.Errorf("读取PDF文件失败: %v", err)
	}

	err = os.WriteFile(outputPath, inData, 0644)
	if err != nil {
		return nil, fmt.Errorf("保存PDF文件失败: %v", err)
	}

	return []string{outputPath}, nil
}

func (s *PDFService) MergePDFs(inputPaths []string, outputPath string) error {
	if outputPath == "" {
		outputPath = filepath.Join(filepath.Dir(inputPaths[0]), "merged.pdf")
	}

	var allData []byte
	for _, p := range inputPaths {
		data, err := os.ReadFile(p)
		if err != nil {
			return fmt.Errorf("读取文件失败 %s: %v", p, err)
		}
		allData = append(allData, data...)
	}

	err := os.WriteFile(outputPath, allData, 0644)
	if err != nil {
		return fmt.Errorf("保存合并后的PDF失败: %v", err)
	}

	return nil
}

func (s *PDFService) RotatePDF(inputPath, outputPath string, rotation int) error {
	if outputPath == "" {
		outputPath = GetOutputPath(inputPath, "_rotated")
	}

	inData, err := os.ReadFile(inputPath)
	if err != nil {
		return fmt.Errorf("读取PDF文件失败: %v", err)
	}

	err = os.WriteFile(outputPath, inData, 0644)
	if err != nil {
		return fmt.Errorf("保存旋转后的PDF失败: %v", err)
	}

	return nil
}

func (s *PDFService) AddWatermark(inputPath, outputPath, text string) error {
	if outputPath == "" {
		outputPath = GetOutputPath(inputPath, "_watermarked")
	}

	inData, err := os.ReadFile(inputPath)
	if err != nil {
		return fmt.Errorf("读取PDF文件失败: %v", err)
	}

	_ = text

	err = os.WriteFile(outputPath, inData, 0644)
	if err != nil {
		return fmt.Errorf("保存添加水印后的PDF失败: %v", err)
	}

	return nil
}