package generate

import (
	"errors"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"strings"
	"testing"
)

func TestGenerateCreatesManifestLoader(t *testing.T) {
	projectDir := newProject(t, `
binary_name = "demo-mcp"
docs_url = "https://docs.example.com/demo"

[bootstrap]
description = "Demo MCP"
`)

	result, err := Generate(Options{ProjectDir: projectDir})
	if err != nil {
		t.Fatalf("Generate returned error: %v", err)
	}

	if !slices.Equal(result.Files, []string{filepath.Join("mcpgen", "manifest.go")}) {
		t.Fatalf("result files = %v", result.Files)
	}

	generatedPath := filepath.Join(projectDir, "mcpgen", "manifest.go")
	content, err := os.ReadFile(generatedPath)
	if err != nil {
		t.Fatalf("ReadFile generated manifest: %v", err)
	}

	for _, snippet := range []string{
		"// Code generated by mcp-framework generate. DO NOT EDIT.",
		"package mcpgen",
		"import fwmanifest \"gitea.lclr.dev/AI/mcp-framework/manifest\"",
		"const embeddedManifest = ",
		"func LoadManifest(startDir string) (fwmanifest.File, string, error) {",
		"return fwmanifest.LoadDefaultOrEmbedded(startDir, embeddedManifest)",
		`binary_name = \"demo-mcp\"`,
	} {
		if !strings.Contains(string(content), snippet) {
			t.Fatalf("generated manifest.go missing snippet %q:\n%s", snippet, content)
		}
	}
}

func TestGenerateIsIdempotentAndCheckDetectsDrift(t *testing.T) {
	projectDir := newProject(t, `binary_name = "demo-mcp"`)

	if _, err := Generate(Options{ProjectDir: projectDir}); err != nil {
		t.Fatalf("first Generate returned error: %v", err)
	}
	generatedPath := filepath.Join(projectDir, "mcpgen", "manifest.go")
	first, err := os.ReadFile(generatedPath)
	if err != nil {
		t.Fatalf("ReadFile first generated file: %v", err)
	}

	if _, err := Generate(Options{ProjectDir: projectDir}); err != nil {
		t.Fatalf("second Generate returned error: %v", err)
	}
	second, err := os.ReadFile(generatedPath)
	if err != nil {
		t.Fatalf("ReadFile second generated file: %v", err)
	}
	if string(second) != string(first) {
		t.Fatalf("second generation changed content")
	}

	if _, err := Generate(Options{ProjectDir: projectDir, Check: true}); err != nil {
		t.Fatalf("check after generation returned error: %v", err)
	}

	if err := os.WriteFile(generatedPath, append(second, []byte("// drift\n")...), 0o600); err != nil {
		t.Fatalf("WriteFile drift: %v", err)
	}

	_, err = Generate(Options{ProjectDir: projectDir, Check: true})
	if !errors.Is(err, ErrGeneratedFilesOutdated) {
		t.Fatalf("check error = %v, want ErrGeneratedFilesOutdated", err)
	}
}

func TestGenerateSupportsManifestAndPackageFlags(t *testing.T) {
	projectDir := t.TempDir()
	manifestPath := filepath.Join(projectDir, "config", "custom.toml")
	if err := os.MkdirAll(filepath.Dir(manifestPath), 0o755); err != nil {
		t.Fatalf("MkdirAll manifest dir: %v", err)
	}
	if err := os.WriteFile(manifestPath, []byte(`binary_name = "demo-mcp"`), 0o600); err != nil {
		t.Fatalf("WriteFile manifest: %v", err)
	}

	result, err := Generate(Options{
		ProjectDir:   projectDir,
		ManifestPath: manifestPath,
		PackageDir:   "internal/generated",
		PackageName:  "generated",
	})
	if err != nil {
		t.Fatalf("Generate returned error: %v", err)
	}

	if !slices.Equal(result.Files, []string{filepath.Join("internal", "generated", "manifest.go")}) {
		t.Fatalf("result files = %v", result.Files)
	}

	content, err := os.ReadFile(filepath.Join(projectDir, "internal", "generated", "manifest.go"))
	if err != nil {
		t.Fatalf("ReadFile generated manifest: %v", err)
	}
	if !strings.Contains(string(content), "package generated") {
		t.Fatalf("generated file should use package name: %s", content)
	}
}

func TestGenerateRejectsInvalidManifest(t *testing.T) {
	projectDir := newProject(t, "[bootstrap\n")

	_, err := Generate(Options{ProjectDir: projectDir})
	if err == nil {
		t.Fatal("expected error")
	}
	if !strings.Contains(err.Error(), "parse manifest") {
		t.Fatalf("error = %v", err)
	}
}

func TestGeneratedLoaderFallsBackToEmbeddedManifest(t *testing.T) {
	projectDir := newProject(t, `
binary_name = "embedded-demo"
docs_url = "https://docs.example.com/embedded"
`)
	writeModule(t, projectDir)

	if _, err := Generate(Options{ProjectDir: projectDir}); err != nil {
		t.Fatalf("Generate returned error: %v", err)
	}

	if err := os.Remove(filepath.Join(projectDir, "mcp.toml")); err != nil {
		t.Fatalf("Remove runtime manifest: %v", err)
	}

	cmd := exec.Command("go", "test", "./...")
	cmd.Dir = projectDir
	output, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("go test generated project: %v\n%s", err, output)
	}
}

func newProject(t *testing.T, manifest string) string {
	t.Helper()

	projectDir := t.TempDir()
	if err := os.WriteFile(filepath.Join(projectDir, "mcp.toml"), []byte(manifest), 0o600); err != nil {
		t.Fatalf("WriteFile manifest: %v", err)
	}
	return projectDir
}

func writeModule(t *testing.T, projectDir string) {
	t.Helper()

	repoRoot, err := filepath.Abs("..")
	if err != nil {
		t.Fatalf("Abs repo root: %v", err)
	}

	goMod := "module example.com/generated-demo\n\ngo 1.25.0\n\nrequire (\n\tgithub.com/BurntSushi/toml v1.6.0\n\tgitea.lclr.dev/AI/mcp-framework v0.0.0\n)\n\nreplace gitea.lclr.dev/AI/mcp-framework => " + filepath.ToSlash(repoRoot) + "\n"
	if err := os.WriteFile(filepath.Join(projectDir, "go.mod"), []byte(goMod), 0o600); err != nil {
		t.Fatalf("WriteFile go.mod: %v", err)
	}

	goSum, err := os.ReadFile(filepath.Join(repoRoot, "go.sum"))
	if err != nil {
		t.Fatalf("ReadFile go.sum: %v", err)
	}
	if err := os.WriteFile(filepath.Join(projectDir, "go.sum"), goSum, 0o600); err != nil {
		t.Fatalf("WriteFile go.sum: %v", err)
	}

	testFile := `package main

import (
	"testing"

	"example.com/generated-demo/mcpgen"
	fwmanifest "gitea.lclr.dev/AI/mcp-framework/manifest"
)

func TestGeneratedLoaderUsesEmbeddedManifest(t *testing.T) {
	file, source, err := mcpgen.LoadManifest(".")
	if err != nil {
		t.Fatalf("LoadManifest returned error: %v", err)
	}
	if source != fwmanifest.EmbeddedSource {
		t.Fatalf("source = %q, want %q", source, fwmanifest.EmbeddedSource)
	}
	if file.BinaryName != "embedded-demo" {
		t.Fatalf("binary name = %q", file.BinaryName)
	}
}
`
	if err := os.WriteFile(filepath.Join(projectDir, "main_test.go"), []byte(testFile), 0o600); err != nil {
		t.Fatalf("WriteFile main_test.go: %v", err)
	}
}