package cmd

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"github.com/fatih/color"
	"github.com/spf13/cobra"

	"gmgauthier.com/grokkit/config"
	"gmgauthier.com/grokkit/internal/grok"
	"gmgauthier.com/grokkit/internal/linter"
	"gmgauthier.com/grokkit/internal/logger"
)

var testgenCmd = &cobra.Command{
	Use:   "testgen PATHS...",
	Short: "Generate AI unit tests for files (Go/Python/C/C++, preview/apply)",
	Long: `Generates comprehensive unit tests matching language conventions.
Supported: Go (table-driven), Python (pytest), C (Check), C++ (Google Test).

Examples:
  grokkit testgen internal/grok/client.go
  grokkit testgen app.py
  grokkit testgen foo.c --yes`,
	Args:         cobra.MinimumNArgs(1),
	SilenceUsage: true,
	Run: func(cmd *cobra.Command, args []string) {
		yesFlag, _ := cmd.Flags().GetBool("yes")
		modelFlag, _ := cmd.Flags().GetString("model")
		model := config.GetModel("testgen", modelFlag)

		logger.Info("testgen started", "num_files", len(args), "model", model, "auto_apply", yesFlag)

		client := grok.NewClient()

		supportedLangs := map[string]bool{"Go": true, "Python": true, "C": true, "C++": true}

		allSuccess := true
		for _, filePath := range args {
			langObj, err := linter.DetectLanguage(filePath)
			if err != nil {
				color.Red("Failed to detect language for %s: %v", filePath, err)
				allSuccess = false
				continue
			}
			lang := langObj.Name
			if !supportedLangs[lang] {
				color.Yellow("Unsupported lang '%s' for %s (supported: Go/Python/C/C++)", lang, filePath)
				allSuccess = false
				continue
			}

			prompt := getTestPrompt(lang)
			if err := processTestgenFile(client, filePath, lang, prompt, model, yesFlag); err != nil {
				allSuccess = false
				color.Red("Failed %s: %v", filePath, err)
				logger.Error("processTestgenFile failed", "file", filePath, "error", err)
			}
		}

		if allSuccess {
			color.Green("\n✅ All test generations complete!")
			color.Yellow("Next steps:\n  make test\n  make test-cover")
		} else {
			color.Red("\n❌ Some files failed.")
			os.Exit(1)
		}
	},
}

func processTestgenFile(client *grok.Client, filePath, lang, systemPrompt, model string, yesFlag bool) error {
	// Validate source file
	srcInfo, err := os.Stat(filePath)
	if err != nil {
		return fmt.Errorf("source file not found: %s", filePath)
	}
	if srcInfo.IsDir() {
		return fmt.Errorf("directories not supported: %s (use files only)", filePath)
	}

	origSrc, err := os.ReadFile(filePath)
	if err != nil {
		return fmt.Errorf("read source: %w", err)
	}
	cleanSrc := removeSourceComments(string(origSrc), lang)

	testPath := getTestFilePath(filePath, lang)

	// Handle existing test file
	var origTest []byte
	testExists := true
	testInfo, err := os.Stat(testPath)
	if os.IsNotExist(err) {
		testExists = false
	} else if err != nil {
		return fmt.Errorf("stat test file: %w", err)
	} else if testInfo.IsDir() {
		return fmt.Errorf("test path is dir: %s", testPath)
	} else {
		origTest, err = os.ReadFile(testPath)
		if err != nil {
			return fmt.Errorf("read existing test: %w", err)
		}
	}

	// Backup existing test
	backupPath := testPath + ".bak"
	if testExists {
		if err := os.WriteFile(backupPath, origTest, 0644); err != nil {
			return fmt.Errorf("backup test file: %w", err)
		}
		color.Yellow("💾 Backup: %s", backupPath)
	}

	// Generate tests
	codeLang := getCodeLang(lang)
	messages := []map[string]string{
		{
			"role":    "system",
			"content": systemPrompt,
		},
		{
			"role":    "user",
			"content": fmt.Sprintf("Source file %s (%s):\n```%s\n%s\n```\n\nGenerate the language-appropriate test file.", filepath.Base(filePath), lang, codeLang, cleanSrc),
		},
	}

	color.Yellow("🤖 Generating tests for %s → %s...", filepath.Base(filePath), filepath.Base(testPath))
	rawResponse := client.StreamSilent(messages, model)
	newTestCode := grok.CleanCodeResponse(rawResponse)

	if len(newTestCode) == 0 || strings.TrimSpace(newTestCode) == "" {
		return fmt.Errorf("empty generation response")
	}

	// Preview
	color.Cyan("\n┌─ Preview: %s ────────────────────────────────────────────────", filepath.Base(testPath))
	if testExists {
		fmt.Println("--- a/" + filepath.Base(testPath))
	} else {
		fmt.Println("--- /dev/null")
	}
	fmt.Println("+++ b/" + filepath.Base(testPath))
	fmt.Print(newTestCode)
	color.Cyan("\n└────────────────────────────────────────────────────────────────")

	if !yesFlag {
		fmt.Print("\nApply? [y/N]: ")
		var confirm string
		_, err := fmt.Scanln(&confirm)
		if err != nil {
			return fmt.Errorf("input error: %w", err)
		}
		confirm = strings.TrimSpace(strings.ToLower(confirm))
		if confirm != "y" && confirm != "yes" {
			color.Yellow("⏭️  Skipped %s (backup: %s)", testPath, backupPath)
			return nil
		}
	}

	// Apply
	if err := os.WriteFile(testPath, []byte(newTestCode), 0644); err != nil {
		return fmt.Errorf("write test file: %w", err)
	}

	color.Green("✅ Wrote %s (%d bytes)", testPath, len(newTestCode))
	logger.Debug("testgen applied", "test_file", testPath, "bytes", len(newTestCode), "source_bytes", len(origSrc))
	return nil
}

func removeSourceComments(content, lang string) string {
	lines := strings.Split(content, "\n")
	var cleanedLines []string
	for _, line := range lines {
		if strings.Contains(line, "Last modified") || strings.Contains(line, "Generated by") ||
			strings.Contains(line, "Generated by testgen") {
			continue
		}
		if lang == "Python" && strings.HasPrefix(strings.TrimSpace(line), "# testgen:") {
			continue
		}
		if (lang == "C" || lang == "C++") && strings.Contains(line, "/* testgen */") {
			continue
		}
		cleanedLines = append(cleanedLines, line)
	}
	return strings.Join(cleanedLines, "\n")
}

func getTestPrompt(lang string) string {
	switch lang {
	case "Go":
		return `You are an expert Go testing specialist. Generate COMPLETE, production-ready unit tests for the provided Go source:

- Table-driven with t.Run(subtest, func(t *testing.T)) and t.Parallel()
- Match exact style of gmgauthier/grokkit/internal/version/version_test.go
- Use t.Context() for ctx-aware tests
- Modern Go 1.24+: slices.Contains/IndexFunc, maps.Keys, errors.Is/Join, any, etc.
- Cover ALL public funcs/methods/fields: happy path, edges, errors, panics, zero values
- Realistic inputs, no external deps/mocks unless code requires
- func TestXxx(t *testing.T) { ... } only

Respond with ONLY the full *_test.go file:
- Correct package name (infer from code)
- Necessary imports
- No benchmarks unless obvious perf func
- NO prose, explanations, markdown, code blocks, or extra text. Pure Go test file.`
	case "Python":
		return `You are a pytest expert. Generate COMPLETE pytest unit tests for the Python source.

- Use pytest fixtures where appropriate
- @pytest.mark.parametrize for tables
- Cover ALL functions/classes/methods: happy/edge/error cases
- pytest.raises for exceptions
- Modern Python 3.12+: type hints, match/case if applicable
- NO external deps unless source requires

Respond ONLY with full test_*.py file: imports, fixtures, tests. Pure Python test code.`
	case "C":
		return `You are a C unit testing expert using Check framework. Generate COMPLETE unit tests for C source.

- Use Check suite: Suite, tcase_begin/end, ck_assert_* macros
- Cover ALL functions: happy/edge/error cases
- Include #include <check.h> <minunit.h>? Use Check std.
- main() runner if needed.

Respond ONLY full test_*.c: headers, suite funcs, main. Pure C.`
	case "C++":
		return `You are a Google Test expert. Generate COMPLETE gtest unit tests for C++ source.

- Use TEST/TEST_F, EXPECT_*/ASSERT_* 
- TYPED_TEST_SUITE if templates
- Cover ALL classes/fns: happy/edge/error
- #include <gtest/gtest.h>

Respond ONLY full test_*.cpp: includes, tests. Pure C++.`
	default:
		return ""
	}
}

func getTestFilePath(filePath, lang string) string {
	ext := filepath.Ext(filePath)
	base := strings.TrimSuffix(filepath.Base(filePath), ext)
	switch lang {
	case "Go":
		dir := filepath.Dir(filePath)
		return filepath.Join(dir, base+"_test.go")
	case "Python":
		return filepath.Join(filepath.Dir(filePath), "test_"+base+".py")
	case "C":
		return filepath.Join(filepath.Dir(filePath), "test_"+base+".c")
	case "C++":
		return filepath.Join(filepath.Dir(filePath), "test_"+base+".cpp")
	default:
		return ""
	}
}

func getCodeLang(lang string) string {
	switch lang {
	case "Go":
		return "go"
	case "Python":
		return "python"
	case "C", "C++":
		return "c"
	default:
		return "text"
	}
}

func init() {
	testgenCmd.Flags().BoolP("yes", "y", false, "Auto-apply without confirmation")
}