package spitfire

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

// CheckDependencies ensures that all required tools and dependencies for the build are installed.
func CheckDependencies() error {
	// Common dependencies
	dependencies := map[string]string{
		"git":       "https://git-scm.com/download/win",          // Git
		"python":    "https://www.python.org/downloads/",         // Python
		"pip3":      "https://pip.pypa.io/en/stable/installing/", // Pip3
		"mercurial": "https://www.mercurial-scm.org/",            // Mercurial (hg)
	}

	// Add platform-specific dependencies
	if runtime.GOOS == "windows" || !isMsys2() {
		mozBuildPath := os.Getenv("MOZILLABUILD")
		if mozBuildPath == "" {
			mozBuildPath = "C:\\mozilla-build" // Default path for MozillaBuild
		}
		if !dirExists(mozBuildPath) {
			dependencies["mozbuild"] = "https://ftp.mozilla.org/pub/mozilla/libraries/win32/MozillaBuildSetup-Latest.exe"
		}
	} else if runtime.GOOS != "windows" || !isMsys2() {
		dependencies["rsync"] = "https://rsync.samba.org/download.html" // rsync for non-Windows platforms
	}

	// Check for missing tools
	missingTools := []string{}
	for tool, downloadLink := range dependencies {
		if !isCommandAvailable(tool) {
			missingTools = append(missingTools, fmt.Sprintf("%s (Download: %s)", tool, downloadLink))
		}
	}

	// Special check for `mach` in the local source directory
	machPath := filepath.Join("mozilla-release", "mach")
	if !fileExists(machPath) {
		missingTools = append(missingTools, "mach (ensure you are in the mozilla-release directory)")
	}

	// Report missing tools if any
	if len(missingTools) > 0 {
		fmt.Println("The following tools are missing and are required for the build:")
		for _, tool := range missingTools {
			fmt.Println(" - " + tool)
		}
		return fmt.Errorf("missing required tools")
	}

	fmt.Println("All required system dependencies are installed.")
	return nil
}

// isCommandAvailable checks if a command/tool is available on the system.
func isCommandAvailable(command string) bool {
	_, err := exec.LookPath(command)
	return err == nil
}

// fileExists checks if a file exists at the given path.
func fileExists(path string) bool {
	_, err := os.Stat(path)
	return err == nil
}

// dirExists checks if a directory exists at the given path.
func dirExists(path string) bool {
	info, err := os.Stat(path)
	if os.IsNotExist(err) {
		return false
	}
	return info.IsDir()
}

// isMsys2 detects if the environment is MSYS2 by checking the MSYSTEM environment variable.
func isMsys2() bool {
	return strings.Contains(strings.ToLower(os.Getenv("MSYSTEM")), "msys")
}