package main

import (
	"bytes"
	"context"
	"io"
	"os"
	"path/filepath"
	"sync/atomic"
	"testing"
	"time"
)

func TestWatchSnapshotExcludesOutput(t *testing.T) {
	dir := t.TempDir()
	out := filepath.Join(dir, "out")
	if err := os.MkdirAll(out, 0o755); err != nil {
		t.Fatal(err)
	}
	src := filepath.Join(dir, "schema.dbml")
	if err := os.WriteFile(src, []byte("a"), 0o644); err != nil {
		t.Fatal(err)
	}
	before := takeWatchSnapshot([]string{dir}, out)
	if err := os.WriteFile(filepath.Join(out, "gen.go"), []byte("x"), 0o644); err != nil {
		t.Fatal(err)
	}
	if after := takeWatchSnapshot([]string{dir}, out); !before.equal(after) {
		t.Errorf("writing into the excluded output path changed the snapshot")
	}
	if err := os.WriteFile(src, []byte("changed"), 0o644); err != nil {
		t.Fatal(err)
	}
	if after := takeWatchSnapshot([]string{dir}, out); before.equal(after) {
		t.Errorf("modifying a source file did not change the snapshot")
	}
}

func TestWatchLoopRerunsOnChange(t *testing.T) {
	dir := t.TempDir()
	src := filepath.Join(dir, "schema.dbml")
	if err := os.WriteFile(src, []byte("a"), 0o644); err != nil {
		t.Fatal(err)
	}

	var runs atomic.Int32
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	done := make(chan struct{})
	go func() {
		defer close(done)
		watchLoop(ctx, io.Discard, []string{src}, "", 10*time.Millisecond, func() error {
			runs.Add(1)
			return nil
		})
	}()

	waitFor(t, func() bool { return runs.Load() == 1 })
	if err := os.WriteFile(src, []byte("changed content"), 0o644); err != nil {
		t.Fatal(err)
	}
	waitFor(t, func() bool { return runs.Load() == 2 })
	cancel()
	<-done
}

func TestRunConvertWatchValidation(t *testing.T) {
	oldPath, oldList, oldDry, oldInt := convertSourcePath, convertFromList, convertDryRun, convertWatchInterval
	defer func() {
		convertSourcePath, convertFromList, convertDryRun, convertWatchInterval = oldPath, oldList, oldDry, oldInt
	}()
	convertSourcePath, convertFromList, convertDryRun, convertWatchInterval = "", nil, false, time.Second
	if err := runConvertWatch(context.Background(), &bytes.Buffer{}, nil); err == nil {
		t.Error("expected error without --from-path/--from-list")
	}
	convertSourcePath, convertDryRun = "x.dbml", true
	if err := runConvertWatch(context.Background(), &bytes.Buffer{}, nil); err == nil {
		t.Error("expected error combining --watch with --dry-run")
	}
}

func waitFor(t *testing.T, cond func() bool) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		if cond() {
			return
		}
		time.Sleep(5 * time.Millisecond)
	}
	t.Fatal("condition not met in time")
}