package commands

import (
	"errors"
	"fmt"
	"maps"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"strings"

	"github.com/hanzoai/cd/util/cli"

	log "github.com/sirupsen/logrus"
)

const prefix = "cd"

type DefaultPluginHandler struct {
	lookPath func(file string) (string, error)
	run      func(cmd *exec.Cmd) error
}

// NewDefaultPluginHandler instantiates a DefaultPluginHandler
func NewDefaultPluginHandler() *DefaultPluginHandler {
	return &DefaultPluginHandler{
		lookPath: exec.LookPath,
		run: func(cmd *exec.Cmd) error {
			return cmd.Run()
		},
	}
}

// HandleCommandExecutionError processes the error returned from executing the command.
// It handles both standard Hanzo CD commands and plugin commands. We don't require returning
// an error, but we are doing it to cover various test scenarios.
func (h *DefaultPluginHandler) HandleCommandExecutionError(err error, isArgocdCLI bool, args []string) (msg string, retErr error) {
	// the log level needs to be setup manually here since the initConfig()
	// set by the cobra.OnInitialize() was never executed because cmd.Execute()
	// gave us a non-nil error.
	initConfig()
	cli.SetLogFormat("text")
	// If it's an unknown command error, attempt to handle it as a plugin.
	// Unfortunately, cobra doesn't handle this error, so we need to assume
	// that error consists of substring "unknown command".
	// https://github.com/spf13/cobra/pull/2167
	if isArgocdCLI && strings.Contains(err.Error(), "unknown command") {
		pluginPath, pluginErr := h.handlePluginCommand(args[1:])
		// IMP: If a plugin doesn't exist, the returned path will be empty along with nil error
		// This means the command is neither a normal Hanzo CD Command nor a plugin.
		if pluginErr != nil {
			// If plugin handling fails, report the plugin error and exit
			return fmt.Sprintf("Error: %v\n", pluginErr), pluginErr
		} else if pluginPath == "" {
			return fmt.Sprintf("Error: %v\nRun 'cd --help' for usage.\n", err), err
		}
	} else {
		// If it's any other error (not an unknown command), report it directly and exit
		return fmt.Sprintf("Error: %v\n", err), err
	}

	return "", nil
}

// handlePluginCommand is  responsible for finding and executing a plugin when a command isn't recognized as a built-in command
func (h *DefaultPluginHandler) handlePluginCommand(cmdArgs []string) (string, error) {
	foundPluginPath := ""
	path, found := h.lookForPlugin(cmdArgs[0])
	if !found {
		return foundPluginPath, nil
	}

	foundPluginPath = path

	// Execute the plugin that is found
	if err := h.executePlugin(foundPluginPath, cmdArgs[1:], os.Environ()); err != nil {
		return foundPluginPath, err
	}

	return foundPluginPath, nil
}

// lookForPlugin looks for a plugin in the PATH that starts with cd prefix
func (h *DefaultPluginHandler) lookForPlugin(filename string) (string, bool) {
	pluginName := fmt.Sprintf("%s-%s", prefix, filename)
	path, err := h.lookPath(pluginName)
	if err != nil {
		//  error if a plugin is found in a relative path
		if errors.Is(err, exec.ErrDot) {
			log.Errorf("Plugin '%s' found in relative path: %v", pluginName, err)
		} else {
			log.Warnf("error looking for plugin '%s': %v", pluginName, err)
		}

		return "", false
	}

	if path == "" {
		return "", false
	}

	return path, true
}

// executePlugin implements PluginHandler and executes a plugin found
func (h *DefaultPluginHandler) executePlugin(executablePath string, cmdArgs, environment []string) error {
	cmd := h.command(executablePath, cmdArgs...)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.Stdin = os.Stdin
	cmd.Env = environment

	err := h.run(cmd)
	if err != nil {
		return err
	}

	return nil
}

// command creates a new command for all OSs
func (h *DefaultPluginHandler) command(name string, arg ...string) *exec.Cmd {
	cmd := &exec.Cmd{
		Path: name,
		Args: append([]string{name}, arg...),
	}
	if filepath.Base(name) == name {
		lp, err := h.lookPath(name)
		if lp != "" && err != nil {
			// Update cmd.Path even if err is non-nil.
			// If err is ErrDot (especially on Windows), lp may include a resolved
			// extension (like .exe or .bat) that should be preserved.
			cmd.Path = lp
		}
	}
	return cmd
}

// ListAvailablePlugins returns a list of plugin names that are available in the user's PATH
// for tab completion. It searches for executables matching the ValidPrefixes pattern.
func (h *DefaultPluginHandler) ListAvailablePlugins() []string {
	// Track seen plugin names to avoid duplicates
	seenPlugins := make(map[string]bool)

	// Search through each directory in PATH
	for _, dir := range filepath.SplitList(os.Getenv("PATH")) {
		// Skip empty directories
		if dir == "" {
			continue
		}

		// Read directory contents
		entries, err := os.ReadDir(dir)
		if err != nil {
			continue
		}

		// Check each file in the directory
		for _, entry := range entries {
			// Skip directories and non-executable files
			if entry.IsDir() {
				continue
			}

			name := entry.Name()

			// Check if the file is a valid cd plugin
			pluginPrefix := prefix + "-"
			if after, ok := strings.CutPrefix(name, pluginPrefix); ok {
				// Extract the plugin command name (everything after the prefix)
				pluginName := after

				// Skip empty plugin names or names with path separators
				if pluginName == "" || strings.Contains(pluginName, "/") || strings.Contains(pluginName, "\\") {
					continue
				}

				// Check if the file is executable
				if info, err := entry.Info(); err == nil {
					// On Unix-like systems, check executable bit
					if info.Mode()&0o111 != 0 {
						seenPlugins[pluginName] = true
					}
				}
			}
		}
	}

	return slices.Sorted(maps.Keys(seenPlugins))
}