//go:build linux || freebsd
// +build linux freebsd

// Package warc provides Web ARChive (WARC) format reading and writing.
// It implements WARC/1.0 as defined by ISO 28500.
package warc

import (
	"fmt"
	"os"
	"time"
)

// Writer writes WARC records to a file.
type Writer struct {
	path string
}

// NewWriter creates a new WARC writer that writes records to the given file.
// Each call to WriteRecord or WriteRecordFile overwrites the file.
func NewWriter(path string) *Writer {
	return &Writer{path: path}
}

// WriteRecord writes a WARC response record from raw byte data.
// targetURI is the original URL of the downloaded resource.
func (w *Writer) WriteRecord(targetURI string, data []byte) error {
	now := time.Now().UTC().Format(time.RFC3339)
	warcData := fmt.Sprintf(
		"WARC/1.0\r\n"+
			"WARC-Type: response\r\n"+
			"WARC-Date: %s\r\n"+
			"WARC-Target-URI: %s\r\n"+
			"Content-Length: %d\r\n"+
			"\r\n"+
			"%s\r\n\r\n",
		now, targetURI, len(data), string(data))

	return os.WriteFile(w.path, []byte(warcData), 0644)
}

// WriteRecordFile reads the file at filePath and writes it as a WARC record.
// targetURI is the original URL of the downloaded resource.
func (w *Writer) WriteRecordFile(targetURI, filePath string) error {
	data, err := os.ReadFile(filePath)
	if err != nil {
		return fmt.Errorf("failed to read file for WARC: %w", err)
	}
	return w.WriteRecord(targetURI, data)
}