//go:build testtool

package main

import (
	"errors"
	"log"
	"net"
	"os"
	"path"
	"slices"
	"strings"
	"syscall"

	"hakurei.app/container/fhs"
	"hakurei.app/container/vfs"
)

func main() {
	log.SetFlags(0)
	log.SetPrefix("testtool: ")

	var hostNet bool
	wantArgs := []string{"testtool"}
	if len(os.Args) == 2 {
		hostNet = true
		wantArgs = []string{"testtool", "net"}
	}
	if !slices.Equal(os.Args, wantArgs) {
		log.Fatalf("Args: %q, want %q", os.Args, wantArgs)
	}

	var overlayRoot bool
	wantEnv := []string{"HAKUREI_TEST=1"}
	if len(os.Environ()) == 2 {
		overlayRoot = true
		wantEnv = []string{"HAKUREI_TEST=1", "HAKUREI_ROOT=1"}
	}
	if !slices.Equal(wantEnv, os.Environ()) {
		log.Fatalf("Environ: %q, want %q", os.Environ(), wantEnv)
	}

	var overlayTmp, overlayWork bool
	const (
		wantExec     = "/opt/bin/testtool"
		wantExecTmp  = "/tmp/bin/testtool"
		wantExecWork = "/work/bin/testtool"
	)
	if got, err := os.Executable(); err != nil {
		log.Fatalf("Executable: error = %v", err)
	} else if got != wantExec {
		switch got {
		case wantExecTmp:
			overlayTmp = true

		case wantExecWork:
			overlayWork = true

		default:
			log.Fatalf("Executable: %q, want %q", got, wantExec)
		}
	}

	wantHostname := "cure"
	if hostNet {
		wantHostname += "-net"
	}

	if hostname, err := os.Hostname(); err != nil {
		log.Fatalf("Hostname: error = %v", err)
	} else if hostname != wantHostname {
		log.Fatalf("Hostname: %q, want %q", hostname, wantHostname)
	}

	var m *vfs.MountInfo
	if f, err := os.Open(fhs.Proc + "self/mountinfo"); err != nil {
		log.Fatalf("Open: error = %v", err)
	} else {
		err = vfs.NewMountInfoDecoder(f).Decode(&m)
		closeErr := f.Close()
		if err != nil {
			log.Fatalf("Decode: error = %v", err)
		}
		if closeErr != nil {
			log.Fatalf("Close: error = %v", err)
		}
	}

	if _, err := net.Dial("tcp", "127.0.0.1:0"); err == nil {
		log.Fatal("Dial unexpectedly succeeded")
	} else if hostNet {
		if !errors.Is(err, syscall.ECONNREFUSED) {
			log.Fatalf("Dial: error = %v", err)
		}
	} else {
		if !errors.Is(err, syscall.ENETUNREACH) {
			log.Fatalf("Dial: error = %v", err)
		}
	}

	const checksumEmptyDir = "MGWmEfjut2QE2xPJwTsmUzpff4BN_FEnQ7T0j7gvUCCiugJQNwqt9m151fm9D1yU"
	ident := "oHuqV7p0v1Vd8IdAzjyYM8sfCS0P2LR5tfv5cb6Gbf2ZWUm8Ec-7hYPJ_qr183m7"
	log.Println(m)
	next := func() { m = m.Next; log.Println(m) }

	if overlayRoot {
		ident = "cIjP14zs5el6W_BQhufL_c0vWg-V6Z6pDpsbEa3sYtZ1381u1bKnH3N16RIrw-1S"

		if m.Root != "/" || m.Target != "/" ||
			m.Source != "overlay" || m.FsType != "overlay" {
			log.Fatal("unexpected root mount entry")
		}
		var lowerdir string
		for _, o := range strings.Split(m.FsOptstr, ",") {
			const lowerdirKey = "lowerdir="
			if strings.HasPrefix(o, lowerdirKey) {
				lowerdir = o[len(lowerdirKey):]
			}
		}
		if path.Base(lowerdir) != checksumEmptyDir {
			log.Fatal("unexpected artifact checksum")
		}
	} else {
		if hostNet {
			ident = "I3T53NtN6HPAyyodHtq2B0clcsoS1nPdvCEb-Zc5K-hoqFGL2od1mftHhwG7gX1S"
		}

		if m.Root != "/sysroot" || m.Target != "/" {
			log.Fatal("unexpected root mount entry")
		}

		next()
		if path.Base(m.Root) != "OLBgp1GsljhM2TJ-sbHjaiH9txEUvgdDTAzHv2P24donTt6_529l-9Ua0vFImLlb" {
			log.Fatal("unexpected file artifact checksum")
		}

		next()
		if path.Base(m.Root) != checksumEmptyDir {
			log.Fatal("unexpected artifact checksum")
		}
	}

	if !overlayTmp {
		next() // testtool artifact
	} else {
		ident = "3ELJ8l42g6XeIoLGR9LheVhMIwSIleD6VrhsliBuon5DAdBOwFSMqd7aiUI4fll7"

		next()
		if path.Base(m.Root) != checksumEmptyDir || m.Target != "/tmp" {
			log.Fatal("unexpected artifact checksum")
		}
	}

	if overlayTmp {
		next() // testtool artifact
		if m.Root != "/" || m.Target != "/tmp" ||
			m.Source != "overlay" || m.FsType != "overlay" {
			log.Fatal("unexpected temp mount entry")
		}
	}

	next()
	if overlayWork {
		ident = "VMCurZKCA_MV80zb-ZBWVytfl3rhYOKJeo2u9l-OuaytQ_w_r4EsqgJ2nfO93x5_"
		if m.Root != "/" || m.Target != "/work" ||
			m.Source != "overlay" || m.FsType != "overlay" {
			log.Fatal("unexpected work mount entry")
		}
	} else {
		if path.Base(m.Root) != ident || m.Target != "/work" {
			log.Fatal("unexpected work mount entry")
		}
	}

	if !overlayTmp {
		next()
		if path.Base(m.Root) != ident || m.Target != "/tmp" {
			log.Fatal("unexpected temp mount entry")
		}
	}

	next()
	if m.Root != "/" || m.Target != "/proc" || m.Source != "proc" || m.FsType != "proc" {
		log.Fatal("unexpected proc mount entry")
	}

	next()
	if m.Root != "/" || m.Target != "/dev" || m.Source != "devtmpfs" || m.FsType != "tmpfs" {
		log.Fatal("unexpected dev mount entry")
	}

	for i := 0; i < 9; i++ { // private /dev entries
		next()
	}

	if m.Next != nil {
		log.Println("unexpected extra mount entries")
		for m.Next != nil {
			next()
		}
		os.Exit(1)
	}

	checkData := []byte{0}
	if hostNet {
		checkData = []byte("net")
	}
	if err := os.WriteFile("check", checkData, 0400); err != nil {
		log.Fatal(err)
	}
}