package extractors

import (
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
)

// PDFExtractor extracts text content from PDF files using pdftotext
type PDFExtractor struct {
	pdftotextPath string
	available     bool
	initError     error
}

// NewPDFExtractor creates a new PDF extractor
func NewPDFExtractor() *PDFExtractor {
	return &PDFExtractor{}
}

// Key returns the unique identifier for this extractor
func (e *PDFExtractor) Key() string {
	return "pdf"
}

// Name returns the human-readable name for this extractor
func (e *PDFExtractor) Name() string {
	return "PDF Text Extractor"
}

// SupportedMimeTypes returns the MIME types this extractor supports
func (e *PDFExtractor) SupportedMimeTypes() []string {
	return []string{"application/pdf"}
}

// Init initializes the extractor by checking if pdftotext is available
func (e *PDFExtractor) Init() error {
	// Check if pdftotext is available in PATH
	path, err := exec.LookPath("pdftotext")
	if err != nil {
		e.available = false
		e.initError = fmt.Errorf("pdftotext binary not found in PATH: %w", err)
		return e.initError
	}

	e.pdftotextPath = path
	e.available = true
	e.initError = nil
	return nil
}

// Extract extracts text content from a PDF file
func (e *PDFExtractor) Extract(ctx context.Context, filePath string) (string, error) {
	if !e.available {
		return "", fmt.Errorf("PDF extractor is not available: %w", e.initError)
	}

	// Open the PDF file
	file, err := os.Open(filePath)
	if err != nil {
		return "", fmt.Errorf("failed to open file: %w", err)
	}
	defer func() { _ = file.Close() }()

	// Create command to run pdftotext
	// Use "-" to read from stdin and output to stdout
	cmd := exec.CommandContext(ctx, e.pdftotextPath, "-", "-")
	cmd.Stdin = file

	// Capture stdout
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		return "", fmt.Errorf("failed to create stdout pipe: %w", err)
	}

	// Start the command
	if err := cmd.Start(); err != nil {
		return "", fmt.Errorf("failed to start pdftotext: %w", err)
	}

	// Read all output
	output, err := io.ReadAll(stdout)
	if err != nil {
		_ = cmd.Wait()
		return "", fmt.Errorf("failed to read output: %w", err)
	}

	// Wait for command to complete
	if err := cmd.Wait(); err != nil {
		return "", fmt.Errorf("pdftotext failed: %w", err)
	}

	return string(output), nil
}

// GetInitError returns the initialization error if any
func (e *PDFExtractor) GetInitError() error {
	return e.initError
}

// IsAvailable returns whether the extractor is available
func (e *PDFExtractor) IsAvailable() bool {
	return e.available
}