package cmd

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"path/filepath"
	"syscall"
	"testing"
	"time"

	"github.com/spf13/cobra"
	"github.com/spf13/viper"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestStartCommand(t *testing.T) {
	// Test start command structure
	assert.Equal(t, "start", startCmd.Use)
	assert.Contains(t, startCmd.Short, "Start")
	assert.Contains(t, startCmd.Long, "registry")
}

func TestRunStart_ConfigError(t *testing.T) {
	// Save original values
	originalCfgFile := cfgFile
	defer func() {
		cfgFile = originalCfgFile
		viper.Reset()
	}()

	// Set non-existent config file
	cfgFile = "/nonexistent/config.toml"
	
	// Capture stderr to check config error message
	var stderr bytes.Buffer
	originalStderr := os.Stderr
	r, w, _ := os.Pipe()
	os.Stderr = w

	// Initialize config to trigger error handling
	done := make(chan bool)
	go func() {
		defer func() {
			if recover() != nil {
				// Recovery from log.Fatal is expected in some cases
			}
			done <- true
		}()
		
		// Call initConfig directly to test config error handling
		initConfig()
	}()

	// Give it a moment to process
	select {
	case <-done:
		// Expected
	case <-time.After(1 * time.Second):
		t.Fatal("initConfig should have completed quickly")
	}

	w.Close()
	os.Stderr = originalStderr
	stderr.ReadFrom(r)

	// Check that an error message was printed
	stderrContent := stderr.String()
	assert.Contains(t, stderrContent, "Error reading config file")
}

func TestCreatePidFile(t *testing.T) {
	// Test PID file creation
	pidFile := createPidFile()
	
	if pidFile != "" {
		// Verify file exists and contains valid PID
		assert.FileExists(t, pidFile)
		
		content, err := os.ReadFile(pidFile)
		require.NoError(t, err)
		
		var pid int
		_, err = fmt.Sscanf(string(content), "%d", &pid)
		assert.NoError(t, err)
		assert.Equal(t, os.Getpid(), pid)
		
		// Clean up
		removePidFile(pidFile)
		assert.NoFileExists(t, pidFile)
	}
	
	// Test should pass even if no writable location is found
	// (function returns empty string in that case)
}

func TestRemovePidFile(t *testing.T) {
	tests := []struct {
		name        string
		setupFunc   func(t *testing.T) string
		expectError bool
	}{
		{
			name: "remove existing file",
			setupFunc: func(t *testing.T) string {
				tempDir := t.TempDir()
				pidFile := filepath.Join(tempDir, "test.pid")
				err := os.WriteFile(pidFile, []byte("12345"), 0644)
				require.NoError(t, err)
				return pidFile
			},
			expectError: false,
		},
		{
			name: "remove non-existent file",
			setupFunc: func(t *testing.T) string {
				tempDir := t.TempDir()
				return filepath.Join(tempDir, "nonexistent.pid")
			},
			expectError: true, // Warning logged, but no panic
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			pidFile := tt.setupFunc(t)
			
			// Should not panic regardless of whether file exists
			assert.NotPanics(t, func() {
				removePidFile(pidFile)
			})
			
			// File should not exist after removal attempt
			assert.NoFileExists(t, pidFile)
		})
	}
}

func TestCreatePidFile_Locations(t *testing.T) {
	// Test that createPidFile tries multiple locations
	// We can't easily mock os.WriteFile to test all failure scenarios,
	// but we can verify the function doesn't panic
	assert.NotPanics(t, func() {
		pidFile := createPidFile()
		if pidFile != "" {
			removePidFile(pidFile)
		}
	})
}

func TestCreatePidFile_Content(t *testing.T) {
	pidFile := createPidFile()
	if pidFile == "" {
		t.Skip("No writable location found for PID file")
	}
	
	defer removePidFile(pidFile)
	
	// Verify PID file contains current process ID
	content, err := os.ReadFile(pidFile)
	require.NoError(t, err)
	
	var storedPid int
	_, err = fmt.Sscanf(string(content), "%d", &storedPid)
	require.NoError(t, err)
	
	assert.Equal(t, os.Getpid(), storedPid)
}

func TestPidFilePermissions(t *testing.T) {
	pidFile := createPidFile()
	if pidFile == "" {
		t.Skip("No writable location found for PID file")
	}
	
	defer removePidFile(pidFile)
	
	// Check file permissions
	info, err := os.Stat(pidFile)
	require.NoError(t, err)
	
	// Should be readable by owner and group
	assert.True(t, info.Mode().Perm()&0644 != 0)
}

func TestPidFileLocations(t *testing.T) {
	// Test different potential PID file locations
	// This mainly tests that the function handles various scenarios
	
	originalHome := os.Getenv("HOME")
	defer os.Setenv("HOME", originalHome)
	
	// Test with invalid home directory
	os.Setenv("HOME", "/nonexistent/invalid/path")
	
	assert.NotPanics(t, func() {
		pidFile := createPidFile()
		if pidFile != "" {
			removePidFile(pidFile)
		}
	})
}

func TestStartCmdStructure(t *testing.T) {
	// Verify command is properly registered
	found := false
	for _, cmd := range rootCmd.Commands() {
		if cmd.Name() == "start" {
			found = true
			break
		}
	}
	assert.True(t, found, "start command should be registered with root command")
}

func TestStartCmdHelp(t *testing.T) {
	var output bytes.Buffer
	
	// Create a copy of the command to avoid affecting the global command
	cmd := &cobra.Command{
		Use:   startCmd.Use,
		Short: startCmd.Short,
		Long:  startCmd.Long,
		Run:   startCmd.Run,
	}
	
	cmd.SetOut(&output)
	cmd.SetErr(&output)
	cmd.SetArgs([]string{"--help"})
	
	err := cmd.Execute()
	assert.NoError(t, err)
	
	helpOutput := output.String()
	assert.Contains(t, helpOutput, "Start")
	assert.Contains(t, helpOutput, "container registry")
	assert.Contains(t, helpOutput, "reverse proxy")
	assert.Contains(t, helpOutput, "server")
}

// Test helper functions for signal handling scenarios
func TestStartCommand_SignalHandling(t *testing.T) {
	// This is a simplified test since we can't easily test the full signal handling
	// without actually starting the server. We mainly test that the command structure is correct.
	
	// Verify the command can be created and has the right properties
	assert.NotNil(t, startCmd.Run)
	assert.Equal(t, "start", startCmd.Use)
}

func TestRunStart_ValidConfig(t *testing.T) {
	// Create a valid config file
	tempDir := t.TempDir()
	configFile := filepath.Join(tempDir, "gordon.toml")
	
	configContent := `
[server]
port = 8080
registry_port = 5000
runtime = "docker"

[logging]
enabled = false
dir = "` + filepath.Join(tempDir, "logs") + `"

[registry]
enabled = false

[routes]
`
	
	err := os.WriteFile(configFile, []byte(configContent), 0644)
	require.NoError(t, err)

	// Save original values
	originalCfgFile := cfgFile
	defer func() {
		cfgFile = originalCfgFile
		viper.Reset()
	}()

	// Set config file
	cfgFile = configFile
	viper.Reset()

	// We can't actually run the full start command without Docker,
	// but we can test that it doesn't immediately fail with config errors
	// by mocking the execution
	
	// This is a limited test since runStart calls log.Fatal on various errors
	// and we can't easily test the full server startup without actual dependencies
	assert.NotNil(t, startCmd.Run, "Start command should have a run function")
}

func TestSignalHandling_Concepts(t *testing.T) {
	// Test the concepts used in signal handling
	
	// Test that we can create signal channels (used in runStart)
	sigChan := make(chan os.Signal, 1)
	reloadChan := make(chan os.Signal, 1)
	
	assert.NotNil(t, sigChan)
	assert.NotNil(t, reloadChan)
	
	// Test signal types that would be used
	signals := []os.Signal{
		syscall.SIGINT,
		syscall.SIGTERM,
		syscall.SIGUSR1,
	}
	
	for _, sig := range signals {
		assert.NotNil(t, sig)
	}
}

func TestContextCancellation(t *testing.T) {
	// Test context cancellation patterns used in runStart
	ctx, cancel := context.WithCancel(context.Background())
	assert.NotNil(t, ctx)
	assert.NotNil(t, cancel)
	
	// Test timeout context
	timeoutCtx, timeoutCancel := context.WithTimeout(context.Background(), 30*time.Second)
	assert.NotNil(t, timeoutCtx)
	assert.NotNil(t, timeoutCancel)
	
	// Clean up
	cancel()
	timeoutCancel()
}