package main

import (
	"bytes"
	"context"
	"io"
	"log"
	"net"
	"os"
	"os/exec"

	guslog "tildegit.org/tjp/gus/contrib/log"
	"tildegit.org/tjp/gus/gemini"
)

func main() {
	// Get TLS files from the environment
	certfile, keyfile := envConfig()

	// build a TLS configuration suitable for gemini
	tlsconf, err := gemini.FileTLS(certfile, keyfile)
	if err != nil {
		log.Fatal(err)
	}

	// set up the network listener
	listener, err := net.Listen("tcp4", ":1965")
	if err != nil {
		log.Fatal(err)
	}

	// add request logging to the request handler
	handler := guslog.Requests(os.Stdout, nil)(cowsayHandler)

	// run the server
	gemini.NewServer(context.Background(), tlsconf, listener, handler).Serve()
}

func cowsayHandler(ctx context.Context, req *gemini.Request) *gemini.Response {
	// prompt for a query if there is none already
	if req.RawQuery == "" {
		return gemini.Input("enter a phrase")
	}

	// find the "cowsay" executable
	binpath, err := exec.LookPath("cowsay")
	if err != nil {
		return gemini.Failure(err)
	}

	// build the command and set the query to be passed to its stdin
	cmd := exec.CommandContext(ctx, binpath)
	cmd.Stdin = bytes.NewBufferString(req.UnescapedQuery())

	// set up a pipe so we can read the command's stdout
	rd, err := cmd.StdoutPipe()
	if err != nil {
		return gemini.Failure(err)
	}

	// start the command
	if err := cmd.Start(); err != nil {
		return gemini.Failure(err)
	}

	// read the complete stdout contents, clean up the process on error
	buf, err := io.ReadAll(rd)
	if err != nil {
		cmd.Process.Kill()
		cmd.Wait()
		return gemini.Failure(err)
	}

	// wait for the process to close
	cmd.Wait()

	// pass the buffer to the response wrapped in ``` toggles,
	// and include a link to start over
	out := io.MultiReader(
		bytes.NewBufferString("```\n"),
		bytes.NewBuffer(buf),
		bytes.NewBufferString("\n```\n=> . again"),
	)
	return gemini.Success("text/gemini", out)
}

func envConfig() (string, string) {
	certfile, ok := os.LookupEnv("SERVER_CERTIFICATE")
	if !ok {
		log.Fatal("missing SERVER_CERTIFICATE environment variable")
	}

	keyfile, ok := os.LookupEnv("SERVER_PRIVATEKEY")
	if !ok {
		log.Fatal("missing SERVER_PRIVATEKEY environment variable")
	}

	return certfile, keyfile
}