package linter

import (
	"os"
	"path/filepath"
	"testing"
)

func TestDetectLanguage(t *testing.T) {
	tests := []struct {
		name     string
		filePath string
		wantLang string
		wantErr  bool
	}{
		{"Go file", "main.go", "Go", false},
		{"Python file", "script.py", "Python", false},
		{"JavaScript file", "app.js", "JavaScript", false},
		{"JSX file", "component.jsx", "JavaScript", false},
		{"TypeScript file", "app.ts", "TypeScript", false},
		{"TSX file", "component.tsx", "TypeScript", false},
		{"Rust file", "main.rs", "Rust", false},
		{"Ruby file", "script.rb", "Ruby", false},
		{"Java file", "Main.java", "Java", false},
		{"C file", "program.c", "C/C++", false},
		{"C++ file", "program.cpp", "C/C++", false},
		{"Header file", "header.h", "C/C++", false},
		{"Shell script", "script.sh", "Shell", false},
		{"Bash script", "script.bash", "Shell", false},
		{"Unsupported file", "file.txt", "", true},
		{"No extension", "Makefile", "", true},
		{"Case insensitive", "MAIN.GO", "Go", false},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			lang, err := DetectLanguage(tt.filePath)
			if tt.wantErr {
				if err == nil {
					t.Errorf("DetectLanguage(%q) expected error, got nil", tt.filePath)
				}
				return
			}
			if err != nil {
				t.Errorf("DetectLanguage(%q) unexpected error: %v", tt.filePath, err)
				return
			}
			if lang.Name != tt.wantLang {
				t.Errorf("DetectLanguage(%q) = %q, want %q", tt.filePath, lang.Name, tt.wantLang)
			}
		})
	}
}

func TestCheckLinterAvailable(t *testing.T) {
	tests := []struct {
		name    string
		linter  Linter
		wantMsg string
	}{
		{
			name: "go command should be available",
			linter: Linter{
				Name:    "go",
				Command: "go",
			},
			wantMsg: "go should be available on system with Go installed",
		},
		{
			name: "nonexistent command",
			linter: Linter{
				Name:    "nonexistent",
				Command: "this-command-does-not-exist-12345",
			},
			wantMsg: "nonexistent command should not be available",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			available := CheckLinterAvailable(tt.linter)
			// We can't assert exact true/false since it depends on the system
			// Just verify the function runs without panic
			t.Logf("%s: available=%v", tt.wantMsg, available)
		})
	}
}

func TestFindAvailableLinter(t *testing.T) {
	// Test with Go language since 'go' command should be available
	// (we're running tests with Go installed)
	t.Run("Go language should find a linter", func(t *testing.T) {
		goLang := &Language{
			Name:       "Go",
			Extensions: []string{".go"},
			Linters: []Linter{
				{
					Name:        "go vet",
					Command:     "go",
					Args:        []string{"vet"},
					InstallInfo: "Built-in with Go",
				},
			},
		}

		linter, err := FindAvailableLinter(goLang)
		if err != nil {
			t.Errorf("FindAvailableLinter(Go) expected to find 'go', got error: %v", err)
		}
		if linter == nil {
			t.Errorf("FindAvailableLinter(Go) returned nil linter")
		} else if linter.Command != "go" {
			t.Errorf("FindAvailableLinter(Go) = %q, want 'go'", linter.Command)
		}
	})

	t.Run("Language with no available linters", func(t *testing.T) {
		fakeLang := &Language{
			Name:       "FakeLang",
			Extensions: []string{".fake"},
			Linters: []Linter{
				{
					Name:        "fakelint",
					Command:     "this-does-not-exist-12345",
					InstallInfo: "not installable",
				},
			},
		}

		linter, err := FindAvailableLinter(fakeLang)
		if err == nil {
			t.Errorf("FindAvailableLinter(FakeLang) expected error, got linter: %v", linter)
		}
		if linter != nil {
			t.Errorf("FindAvailableLinter(FakeLang) expected nil linter, got: %v", linter)
		}
	})
}

func TestRunLinter(t *testing.T) {
	// Create a temporary Go file with a simple error
	tmpDir := t.TempDir()
	testFile := filepath.Join(tmpDir, "test.go")

	// Valid Go code
	validCode := `package main

import "fmt"

func main() {
	fmt.Println("Hello, World!")
}
`
	if err := os.WriteFile(testFile, []byte(validCode), 0644); err != nil {
		t.Fatalf("Failed to create test file: %v", err)
	}

	t.Run("Run go vet on valid file", func(t *testing.T) {
		linter := Linter{
			Name:    "go vet",
			Command: "go",
			Args:    []string{"vet"},
		}

		result, err := RunLinter(testFile, linter)
		if err != nil {
			t.Errorf("RunLinter() unexpected error: %v", err)
		}
		if result == nil {
			t.Fatal("RunLinter() returned nil result")
		}
		if !result.LinterExists {
			t.Errorf("RunLinter() LinterExists = false, want true")
		}
		if result.LinterUsed != "go vet" {
			t.Errorf("RunLinter() LinterUsed = %q, want 'go vet'", result.LinterUsed)
		}
		// Note: go vet might find issues or not, so we don't assert HasIssues
		t.Logf("go vet result: ExitCode=%d, HasIssues=%v, Output=%q",
			result.ExitCode, result.HasIssues, result.Output)
	})

	t.Run("Run nonexistent linter", func(t *testing.T) {
		linter := Linter{
			Name:    "fake",
			Command: "this-does-not-exist-12345",
			Args:    []string{},
		}

		result, err := RunLinter(testFile, linter)
		if err == nil {
			t.Errorf("RunLinter() expected error for nonexistent command, got result: %v", result)
		}
	})
}

func TestLintFile(t *testing.T) {
	tmpDir := t.TempDir()

	t.Run("Lint valid Go file", func(t *testing.T) {
		testFile := filepath.Join(tmpDir, "valid.go")
		validCode := `package main

import "fmt"

func main() {
	fmt.Println("Hello, World!")
}
`
		if err := os.WriteFile(testFile, []byte(validCode), 0644); err != nil {
			t.Fatalf("Failed to create test file: %v", err)
		}

		result, err := LintFile(testFile)
		if err != nil {
			t.Errorf("LintFile() unexpected error: %v", err)
		}
		if result == nil {
			t.Fatal("LintFile() returned nil result")
		}
		if result.Language != "Go" {
			t.Errorf("LintFile() Language = %q, want 'Go'", result.Language)
		}
		if !result.LinterExists {
			t.Errorf("LintFile() LinterExists = false, want true")
		}
	})

	t.Run("Lint nonexistent file", func(t *testing.T) {
		testFile := filepath.Join(tmpDir, "nonexistent.go")

		result, err := LintFile(testFile)
		if err == nil {
			t.Errorf("LintFile() expected error for nonexistent file, got result: %v", result)
		}
	})

	t.Run("Lint unsupported file type", func(t *testing.T) {
		testFile := filepath.Join(tmpDir, "test.txt")
		if err := os.WriteFile(testFile, []byte("hello"), 0644); err != nil {
			t.Fatalf("Failed to create test file: %v", err)
		}

		result, err := LintFile(testFile)
		if err == nil {
			t.Errorf("LintFile() expected error for unsupported file type, got result: %v", result)
		}
	})
}

func TestGetSupportedLanguages(t *testing.T) {
	langs := GetSupportedLanguages()

	if len(langs) == 0 {
		t.Errorf("GetSupportedLanguages() returned empty list")
	}

	// Check that we have some expected languages
	expectedLangs := []string{"Go", "Python", "JavaScript", "TypeScript"}
	for _, expected := range expectedLangs {
		found := false
		for _, lang := range langs {
			if contains(lang, expected) {
				found = true
				break
			}
		}
		if !found {
			t.Errorf("GetSupportedLanguages() missing expected language: %s", expected)
		}
	}

	// Verify format includes extensions
	for _, lang := range langs {
		if !contains(lang, "(") || !contains(lang, ")") {
			t.Errorf("GetSupportedLanguages() entry missing format 'Name (extensions)': %s", lang)
		}
	}
}

func TestLanguageStructure(t *testing.T) {
	// Verify the languages slice is properly structured
	if len(languages) == 0 {
		t.Fatal("languages slice is empty")
	}

	for _, lang := range languages {
		if lang.Name == "" {
			t.Errorf("Language with empty Name found")
		}
		if len(lang.Extensions) == 0 {
			t.Errorf("Language %q has no extensions", lang.Name)
		}
		if len(lang.Linters) == 0 {
			t.Errorf("Language %q has no linters", lang.Name)
		}

		// Check extensions start with dot
		for _, ext := range lang.Extensions {
			if ext == "" || ext[0] != '.' {
				t.Errorf("Language %q has invalid extension: %q", lang.Name, ext)
			}
		}

		// Check linters have required fields
		for _, linter := range lang.Linters {
			if linter.Name == "" {
				t.Errorf("Language %q has linter with empty Name", lang.Name)
			}
			if linter.Command == "" {
				t.Errorf("Language %q has linter %q with empty Command", lang.Name, linter.Name)
			}
			if linter.InstallInfo == "" {
				t.Errorf("Language %q has linter %q with empty InstallInfo", lang.Name, linter.Name)
			}
		}
	}
}

// Helper function
func contains(s, substr string) bool {
	return len(s) >= len(substr) && (s == substr || len(s) > len(substr) &&
		(s[:len(substr)] == substr || s[len(s)-len(substr):] == substr ||
		containsMiddle(s, substr)))
}

func containsMiddle(s, substr string) bool {
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}