package main

import (
	"crypto/sha256"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"testing"
)

const protoFreshnessHelperEnv = "CHECK_SAFETY_PROTO_FRESHNESS_HELPER"

func TestDiffProtoOutputsIsDeterministic(t *testing.T) {
	before := map[string]protoOutputState{
		"packages/api/src/unchanged.ts": {digest: [sha256.Size]byte{1}},
		"packages/api/src/modified.ts":  {digest: [sha256.Size]byte{2}},
		"packages/api/src/removed.ts":   {digest: [sha256.Size]byte{3}},
	}
	after := map[string]protoOutputState{
		"packages/api/src/unchanged.ts": {digest: [sha256.Size]byte{1}},
		"packages/api/src/modified.ts":  {digest: [sha256.Size]byte{4}},
		"packages/api/src/added.ts":     {digest: [sha256.Size]byte{5}},
	}

	want := strings.Join([]string{
		"?? packages/api/src/added.ts",
		" M packages/api/src/modified.ts",
		" D packages/api/src/removed.ts",
	}, "\n")
	if got := strings.Join(diffProtoOutputs(before, after), "\n"); got != want {
		t.Fatalf("diffProtoOutputs() = %q, want %q", got, want)
	}
}

func TestDiffProtoOutputsIgnoresPermissionDifferences(t *testing.T) {
	digest := [sha256.Size]byte{1}
	before := map[string]protoOutputState{
		"packages/api/src/example.ts": {mode: 0o660, digest: digest},
	}
	after := map[string]protoOutputState{
		"packages/api/src/example.ts": {mode: 0o644, digest: digest},
	}

	if got := diffProtoOutputs(before, after); len(got) != 0 {
		t.Fatalf("diffProtoOutputs() = %v, want permissions-only change ignored", got)
	}
}

func TestCheckProtoGeneratedFreshnessInSandboxLeavesSourceUntouched(t *testing.T) {
	repoRoot := newProtoFreshnessTestRepo(t, "@printf 'generated\\n' > packages/api/src/example.ts")
	tempParent := t.TempDir()

	result, err := checkProtoGeneratedFreshnessInSandbox(repoRoot, tempParent)
	if err != nil {
		t.Fatalf("checkProtoGeneratedFreshnessInSandbox() error = %v\n%s", err, result.output)
	}
	if !result.checked {
		t.Fatal("checkProtoGeneratedFreshnessInSandbox() checked = false, want true")
	}
	if !result.changed() {
		t.Fatal("checkProtoGeneratedFreshnessInSandbox() changed = false, want true")
	}
	if result.beforeStatus != "" {
		t.Fatalf("beforeStatus = %q, want clean", result.beforeStatus)
	}
	if result.afterStatus != " M packages/api/src/example.ts" {
		t.Fatalf("afterStatus = %q, want modified generated file", result.afterStatus)
	}
	assertProtoTestSourceAndSandboxesClean(t, repoRoot, tempParent)
}

func TestCheckProtoGeneratedFreshnessInSandboxReportsClean(t *testing.T) {
	repoRoot := newProtoFreshnessTestRepo(t, "@:")
	tempParent := t.TempDir()

	result, err := checkProtoGeneratedFreshnessInSandbox(repoRoot, tempParent)
	if err != nil {
		t.Fatalf("checkProtoGeneratedFreshnessInSandbox() error = %v\n%s", err, result.output)
	}
	if result.changed() {
		t.Fatalf("checkProtoGeneratedFreshnessInSandbox() changed = true, status = %q", result.afterStatus)
	}
	assertProtoTestSourceAndSandboxesClean(t, repoRoot, tempParent)
}

func TestCheckProtoGeneratedFreshnessInSandboxCleansUpAfterFailure(t *testing.T) {
	repoRoot := newProtoFreshnessTestRepo(t, "@printf 'partial\\n' > packages/api/src/example.ts; printf 'generator failed\\n' >&2; exit 7")
	tempParent := t.TempDir()

	result, err := checkProtoGeneratedFreshnessInSandbox(repoRoot, tempParent)
	if err == nil {
		t.Fatal("checkProtoGeneratedFreshnessInSandbox() error = nil, want generator failure")
	}
	if !strings.Contains(err.Error(), "make proto failed") {
		t.Fatalf("error = %q, want make proto context", err)
	}
	if !strings.Contains(result.output, "generator failed") {
		t.Fatalf("output = %q, want generator stderr", result.output)
	}
	assertProtoTestSourceAndSandboxesClean(t, repoRoot, tempParent)
}

func TestCheckProtoGeneratedFreshnessConcurrentProcesses(t *testing.T) {
	repoRoot := newProtoFreshnessTestRepo(t, "@mkdir generation-exclusive; sleep 0.05; printf 'generated in %s\\n' \"$$PWD\" > packages/api/src/example.ts")
	tempParent := t.TempDir()
	testBinary, err := os.Executable()
	if err != nil {
		t.Fatalf("resolve test executable: %v", err)
	}

	const processCount = 6
	type processResult struct {
		index  int
		output string
		err    error
	}
	results := make(chan processResult, processCount)

	var workers sync.WaitGroup
	for index := range processCount {
		workers.Go(func() {
			cmd := exec.CommandContext(t.Context(), testBinary, "-test.run=^TestProtoFreshnessHelperProcess$")
			cmd.Env = append(os.Environ(),
				protoFreshnessHelperEnv+"=1",
				"CHECK_SAFETY_PROTO_REPO="+repoRoot,
				"CHECK_SAFETY_PROTO_TEMP_PARENT="+tempParent,
			)
			output, runErr := cmd.CombinedOutput()
			results <- processResult{index: index, output: string(output), err: runErr}
		})
	}
	workers.Wait()
	close(results)

	for result := range results {
		if result.err != nil {
			t.Errorf("checker process %d failed: %v\n%s", result.index, result.err, result.output)
		}
	}
	assertProtoTestSourceAndSandboxesClean(t, repoRoot, tempParent)
}

func TestProtoFreshnessHelperProcess(t *testing.T) {
	if os.Getenv(protoFreshnessHelperEnv) != "1" {
		return
	}

	repoRoot := os.Getenv("CHECK_SAFETY_PROTO_REPO")
	tempParent := os.Getenv("CHECK_SAFETY_PROTO_TEMP_PARENT")
	result, err := checkProtoGeneratedFreshnessInSandbox(repoRoot, tempParent)
	if err != nil {
		t.Fatalf("checkProtoGeneratedFreshnessInSandbox() error = %v\n%s", err, result.output)
	}
	if !result.changed() {
		t.Fatal("checkProtoGeneratedFreshnessInSandbox() changed = false, want true")
	}
}

func newProtoFreshnessTestRepo(t *testing.T, recipe string) string {
	t.Helper()
	if _, err := exec.LookPath("make"); err != nil {
		t.Skip("make is required for proto freshness integration coverage")
	}

	repoRoot := t.TempDir()
	writeTestFile(t, filepath.Join(repoRoot, "Makefile"), ".PHONY: proto\nproto:\n\t"+recipe+"\n", 0o644)
	writeTestFile(t, filepath.Join(repoRoot, "buf.gen.yaml"), "version: v2\n", 0o644)
	writeTestFile(t, filepath.Join(repoRoot, "packages", "api", "src", "example.ts"), "source\n", 0o644)
	return repoRoot
}

func assertProtoTestSourceAndSandboxesClean(t *testing.T, repoRoot, tempParent string) {
	t.Helper()

	content, err := os.ReadFile(filepath.Join(repoRoot, "packages", "api", "src", "example.ts"))
	if err != nil {
		t.Fatalf("read source generated file: %v", err)
	}
	if string(content) != "source\n" {
		t.Fatalf("source generated file = %q, want unchanged", content)
	}

	entries, err := os.ReadDir(tempParent)
	if err != nil {
		t.Fatalf("read sandbox parent: %v", err)
	}
	if len(entries) != 0 {
		t.Fatalf("sandbox parent contains residual entries: %v", entries)
	}
}