package main

import (
	"archive/tar"
	"bufio"
	"compress/gzip"
	"errors"
	"fmt"
	"io"
	"net/http"
	"os"
	"strconv"

	flag "github.com/spf13/pflag"
)

func main() {
	var (
		url          = flag.StringP("url", "u", "", "Url to the APKINDEX.tar.gz")
		output       = flag.StringP("output", "o", "index.md", "Output path")
		templateType = flag.StringP("template-type", "t", "text", "Template system to be used, options: html, text")
		templateFile = flag.StringP("template-file", "f", "text", "Template file to be used")
	)
	flag.Parse()

	err := run(
		*url,
		*output,
		*templateType,
		*templateFile,
	)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}

func run(
	url string,
	output string,
	templateType string,
	templateFile string,
) error {

	tarStream, err := fechIndex(url)
	if err != nil {
		return fmt.Errorf("Error fecthing index file: %w", err)
	}

	defer tarStream.Close()

	archive, err := gzip.NewReader(tarStream)
	if err != nil {
		return fmt.Errorf("Error creating gzip reader: %w", err)
	}

	tr := tar.NewReader(archive)

	for {
		h, err := tr.Next()
		if err != nil {
			return fmt.Errorf("Error reading next tar entry: %w", err)
		}

		if h.FileInfo().Name() == "APKINDEX" {
			break
		}
	}

	var (
		s       = bufio.NewScanner(tr)
		entries = make([]*Entry, 0)
		lines   = make([]string, 0)
	)

	for s.Scan() {
		l := s.Text()
		if l == "" {
			entry := Parse(lines)
			entries = append(entries, entry)
			lines = make([]string, 0)
		} else {
			lines = append(lines, l)
		}
	}

	outputFile, err := getOutputFile(output)
	if err != nil {
		return fmt.Errorf("Error openning output file: %w", err)
	}

	tmpl, err := GetTemplate(templateType, templateFile)
	if err != nil {
		return fmt.Errorf("Error loading template file: %w", err)
	}

	err = tmpl.Execute(outputFile, entries)
	if err != nil {
		return fmt.Errorf("Error executing template: %w", err)
	}
	return nil
}

func getOutputFile(output string) (*os.File, error) {
	if output != "" {
		outputFile, err := os.Create(output)
		if err != nil {
			return nil, err
		}
		return outputFile, nil
	} else {
		return os.Stdout, nil
	}
}

func fechIndex(url string) (io.ReadCloser, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}

	if resp.StatusCode != 200 {
		return nil, errors.New("Http error " + strconv.Itoa(resp.StatusCode))
	}

	return resp.Body, nil
}