package bootstrap

import (
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"sort"
	"strings"
)

const (
	CommandSetup   = "setup"
	CommandLogin   = "login"
	CommandMCP     = "mcp"
	CommandConfig  = "config"
	CommandUpdate  = "update"
	CommandVersion = "version"
	CommandDoctor  = "doctor"

	bitwardenDebugEnvName = "MCP_FRAMEWORK_BITWARDEN_DEBUG"

	ConfigSubcommandShow   = "show"
	ConfigSubcommandTest   = "test"
	ConfigSubcommandDelete = "delete"
)

var (
	ErrBinaryNameRequired   = errors.New("binary name is required")
	ErrUnknownCommand       = errors.New("unknown command")
	ErrUnknownSubcommand    = errors.New("unknown subcommand")
	ErrCommandNotConfigured = errors.New("command not configured")
	ErrVersionRequired      = errors.New("version is required when no version hook is configured")
	ErrSubcommandRequired   = errors.New("subcommand is required")
)

type Handler func(context.Context, Invocation) error

type Hooks struct {
	Setup        Handler
	Login        Handler
	MCP          Handler
	Config       Handler
	ConfigShow   Handler
	ConfigTest   Handler
	ConfigDelete Handler
	Update       Handler
	Version      Handler
}

type Options struct {
	BinaryName           string
	Description          string
	Version              string
	Aliases              map[string][]string
	AliasDescriptions    map[string]string
	EnableDoctorAlias    bool
	DisabledCommands     []string
	Args                 []string
	Stdin                io.Reader
	Stdout               io.Writer
	Stderr               io.Writer
	Hooks                Hooks
}

type Invocation struct {
	Command string
	Args    []string
	Stdin   io.Reader
	Stdout  io.Writer
	Stderr  io.Writer
}

type commandDef struct {
	Name        string
	Description string
	Handler     func(Hooks) Handler
}

var commands = []commandDef{
	{
		Name:        CommandSetup,
		Description: "Initialiser ou mettre a jour la configuration locale.",
		Handler: func(h Hooks) Handler {
			return h.Setup
		},
	},
	{
		Name:        CommandLogin,
		Description: "Authentifier et deverrouiller Bitwarden pour persister BW_SESSION.",
		Handler: func(h Hooks) Handler {
			return h.Login
		},
	},
	{
		Name:        CommandMCP,
		Description: "Executer la logique MCP principale du binaire.",
		Handler: func(h Hooks) Handler {
			return h.MCP
		},
	},
	{
		Name:        CommandConfig,
		Description: "Inspecter ou modifier la configuration.",
		Handler: func(h Hooks) Handler {
			return h.Config
		},
	},
	{
		Name:        CommandUpdate,
		Description: "Declencher le flux d'auto-update.",
		Handler: func(h Hooks) Handler {
			return h.Update
		},
	},
	{
		Name:        CommandVersion,
		Description: "Afficher la version du binaire.",
		Handler: func(h Hooks) Handler {
			return h.Version
		},
	},
}

func Run(ctx context.Context, opts Options) error {
	normalized := normalize(opts)

	if strings.TrimSpace(normalized.BinaryName) == "" {
		return ErrBinaryNameRequired
	}

	resolvedArgs := expandAliases(normalized.Args, normalized.Aliases)
	resolvedArgs, debugEnabled := extractGlobalDebugFlag(resolvedArgs)
	if debugEnabled {
		_ = os.Setenv(bitwardenDebugEnvName, "1")
	}

	command, commandArgs, showHelp := parseArgs(resolvedArgs)
	if showHelp {
		return printHelp(normalized, command, commandArgs)
	}

	if command == "" {
		return printHelp(normalized, "")
	}

	if isCommandDisabled(command, normalized.DisabledCommands) {
		return fmt.Errorf("%w: %s", ErrUnknownCommand, command)
	}

	if command == CommandConfig {
		return runConfigCommand(ctx, normalized, commandArgs)
	}

	handler, known := resolveHandler(command, normalized.Hooks)
	if !known {
		return fmt.Errorf("%w: %s", ErrUnknownCommand, command)
	}

	if handler == nil {
		switch command {
		case CommandVersion:
			if strings.TrimSpace(normalized.Version) == "" {
				return ErrVersionRequired
			}
			_, err := fmt.Fprintln(normalized.Stdout, normalized.Version)
			return err
		default:
			return fmt.Errorf("%w: %s", ErrCommandNotConfigured, command)
		}
	}

	return handler(ctx, Invocation{
		Command: command,
		Args:    commandArgs,
		Stdin:   normalized.Stdin,
		Stdout:  normalized.Stdout,
		Stderr:  normalized.Stderr,
	})
}

func normalize(opts Options) Options {
	if opts.Stdin == nil {
		opts.Stdin = os.Stdin
	}
	if opts.Stdout == nil {
		opts.Stdout = os.Stdout
	}
	if opts.Stderr == nil {
		opts.Stderr = os.Stderr
	}
	if opts.Args == nil {
		opts.Args = os.Args[1:]
	}
	opts.Aliases = normalizeAliases(opts.Aliases, opts.EnableDoctorAlias)
	opts.AliasDescriptions = normalizeAliasDescriptions(opts.AliasDescriptions, opts.Aliases, opts.EnableDoctorAlias)
	for _, cmd := range autoDisabledCommands(opts) {
		if !isCommandDisabled(cmd, opts.DisabledCommands) {
			opts.DisabledCommands = append(opts.DisabledCommands, cmd)
		}
	}
	return opts
}

func normalizeAliases(aliases map[string][]string, enableDoctorAlias bool) map[string][]string {
	normalized := make(map[string][]string, len(aliases)+1)
	for name, target := range aliases {
		trimmedName := strings.TrimSpace(name)
		trimmedTarget := trimArgs(target)
		if trimmedName == "" || len(trimmedTarget) == 0 {
			continue
		}
		normalized[trimmedName] = trimmedTarget
	}

	if enableDoctorAlias {
		if _, ok := normalized[CommandDoctor]; !ok {
			normalized[CommandDoctor] = []string{CommandConfig, ConfigSubcommandTest}
		}
	}

	if len(normalized) == 0 {
		return nil
	}
	return normalized
}

func normalizeAliasDescriptions(descriptions map[string]string, aliases map[string][]string, enableDoctorAlias bool) map[string]string {
	normalized := make(map[string]string, len(descriptions)+1)
	for name, description := range descriptions {
		trimmedName := strings.TrimSpace(name)
		trimmedDescription := strings.TrimSpace(description)
		if trimmedName == "" || trimmedDescription == "" {
			continue
		}
		if _, ok := aliases[trimmedName]; !ok {
			continue
		}
		normalized[trimmedName] = trimmedDescription
	}

	if enableDoctorAlias {
		if _, ok := aliases[CommandDoctor]; ok {
			if _, defined := normalized[CommandDoctor]; !defined {
				normalized[CommandDoctor] = "Diagnostiquer la configuration locale."
			}
		}
	}

	if len(normalized) == 0 {
		return nil
	}
	return normalized
}

func parseArgs(args []string) (command string, commandArgs []string, showHelp bool) {
	args = trimArgs(args)
	if len(args) == 0 {
		return "", nil, false
	}

	first := strings.TrimSpace(args[0])
	switch first {
	case "help", "-h", "--help":
		if len(args) > 1 {
			return strings.TrimSpace(args[1]), trimArgs(args[2:]), true
		}
		return "", nil, true
	}

	command = first
	commandArgs = trimArgs(args[1:])
	if len(commandArgs) > 0 {
		last := strings.TrimSpace(commandArgs[len(commandArgs)-1])
		if last == "-h" || last == "--help" {
			return command, commandArgs[:len(commandArgs)-1], true
		}
	}

	return command, commandArgs, false
}

func extractGlobalDebugFlag(args []string) ([]string, bool) {
	args = trimArgs(args)
	if len(args) == 0 {
		return nil, false
	}

	filtered := make([]string, 0, len(args))
	debugEnabled := false
	for _, arg := range args {
		if strings.TrimSpace(arg) == "--debug" {
			debugEnabled = true
			continue
		}
		filtered = append(filtered, arg)
	}

	return filtered, debugEnabled
}

func expandAliases(args []string, aliases map[string][]string) []string {
	args = trimArgs(args)
	if len(args) == 0 || len(aliases) == 0 {
		return args
	}

	if args[0] == "help" && len(args) > 1 {
		expanded, ok := resolveAlias(aliases, args[1])
		if !ok {
			return args
		}

		withHelp := make([]string, 0, 1+len(expanded)+len(args[2:]))
		withHelp = append(withHelp, "help")
		withHelp = append(withHelp, expanded...)
		withHelp = append(withHelp, args[2:]...)
		return withHelp
	}

	expanded, ok := resolveAlias(aliases, args[0])
	if !ok {
		return args
	}

	withCommand := make([]string, 0, len(expanded)+len(args[1:]))
	withCommand = append(withCommand, expanded...)
	withCommand = append(withCommand, args[1:]...)

	if len(withCommand) == 0 {
		return args
	}

	last := strings.TrimSpace(withCommand[len(withCommand)-1])
	if last != "-h" && last != "--help" {
		return withCommand
	}

	helpArgs := make([]string, 0, len(withCommand))
	helpArgs = append(helpArgs, "help")
	helpArgs = append(helpArgs, withCommand[:len(withCommand)-1]...)
	return helpArgs
}

func resolveAlias(aliases map[string][]string, command string) ([]string, bool) {
	target, ok := aliases[strings.TrimSpace(command)]
	if !ok {
		return nil, false
	}

	expanded := trimArgs(target)
	if len(expanded) == 0 {
		return nil, false
	}

	return expanded, true
}

func trimArgs(args []string) []string {
	if len(args) == 0 {
		return nil
	}

	result := make([]string, 0, len(args))
	for _, arg := range args {
		trimmed := strings.TrimSpace(arg)
		if trimmed == "" {
			continue
		}
		result = append(result, trimmed)
	}
	return result
}

func runConfigCommand(ctx context.Context, opts Options, args []string) error {
	if len(args) == 0 {
		return fmt.Errorf(
			"%w: %s requires one of: %s, %s, %s",
			ErrSubcommandRequired,
			CommandConfig,
			ConfigSubcommandShow,
			ConfigSubcommandTest,
			ConfigSubcommandDelete,
		)
	}

	subcommand := strings.TrimSpace(args[0])
	subcommandArgs := args[1:]

	handler, known := resolveConfigHandler(opts.Hooks, subcommand)
	if !known {
		if opts.Hooks.Config != nil {
			return opts.Hooks.Config(ctx, Invocation{
				Command: CommandConfig,
				Args:    args,
				Stdin:   opts.Stdin,
				Stdout:  opts.Stdout,
				Stderr:  opts.Stderr,
			})
		}
		return fmt.Errorf("%w: %s %s", ErrUnknownSubcommand, CommandConfig, subcommand)
	}

	if handler == nil {
		if opts.Hooks.Config != nil {
			return opts.Hooks.Config(ctx, Invocation{
				Command: fmt.Sprintf("%s %s", CommandConfig, subcommand),
				Args:    subcommandArgs,
				Stdin:   opts.Stdin,
				Stdout:  opts.Stdout,
				Stderr:  opts.Stderr,
			})
		}
		return fmt.Errorf("%w: %s %s", ErrCommandNotConfigured, CommandConfig, subcommand)
	}

	return handler(ctx, Invocation{
		Command: fmt.Sprintf("%s %s", CommandConfig, subcommand),
		Args:    subcommandArgs,
		Stdin:   opts.Stdin,
		Stdout:  opts.Stdout,
		Stderr:  opts.Stderr,
	})
}

func resolveConfigHandler(hooks Hooks, subcommand string) (Handler, bool) {
	switch subcommand {
	case ConfigSubcommandShow:
		return hooks.ConfigShow, true
	case ConfigSubcommandTest:
		return hooks.ConfigTest, true
	case ConfigSubcommandDelete:
		return hooks.ConfigDelete, true
	default:
		return nil, false
	}
}

func resolveHandler(command string, hooks Hooks) (Handler, bool) {
	for _, def := range commands {
		if def.Name == command {
			return def.Handler(hooks), true
		}
	}
	return nil, false
}

func printHelp(opts Options, command string, args ...[]string) error {
	var commandArgs []string
	if len(args) > 0 {
		commandArgs = args[0]
	}

	if command == "" {
		return printGlobalHelp(opts)
	}

	if isCommandDisabled(command, opts.DisabledCommands) {
		return fmt.Errorf("%w: %s", ErrUnknownCommand, command)
	}

	if command == CommandConfig {
		return printConfigHelp(opts, commandArgs)
	}

	for _, def := range commands {
		if def.Name != command {
			continue
		}
		_, err := fmt.Fprintf(
			opts.Stdout,
			"Usage:\n  %s %s [args]\n\n%s\n",
			opts.BinaryName,
			def.Name,
			def.Description,
		)
		return err
	}

	return fmt.Errorf("%w: %s", ErrUnknownCommand, command)
}

func printConfigHelp(opts Options, args []string) error {
	if len(args) == 0 {
		_, err := fmt.Fprintf(
			opts.Stdout,
			"Usage:\n  %s config <subcommand> [args]\n\nSubcommandes:\n  %-7s Afficher la configuration résolue et la provenance des valeurs.\n  %-7s Vérifier la configuration et la connectivité.\n  %-7s Supprimer un profil local (optionnel).\n",
			opts.BinaryName,
			ConfigSubcommandShow,
			ConfigSubcommandTest,
			ConfigSubcommandDelete,
		)
		return err
	}

	switch args[0] {
	case ConfigSubcommandShow:
		_, err := fmt.Fprintf(
			opts.Stdout,
			"Usage:\n  %s config %s [args]\n\nAfficher la configuration résolue et l'origine des valeurs.\n",
			opts.BinaryName,
			ConfigSubcommandShow,
		)
		return err
	case ConfigSubcommandTest:
		_, err := fmt.Fprintf(
			opts.Stdout,
			"Usage:\n  %s config %s [args]\n\nTester la configuration résolue et la connectivité associée.\n",
			opts.BinaryName,
			ConfigSubcommandTest,
		)
		return err
	case ConfigSubcommandDelete:
		_, err := fmt.Fprintf(
			opts.Stdout,
			"Usage:\n  %s config %s [args]\n\nSupprimer un profil local de configuration.\n",
			opts.BinaryName,
			ConfigSubcommandDelete,
		)
		return err
	default:
		return fmt.Errorf("%w: %s %s", ErrUnknownSubcommand, CommandConfig, args[0])
	}
}

func printGlobalHelp(opts Options) error {
	if strings.TrimSpace(opts.Description) != "" {
		if _, err := fmt.Fprintf(opts.Stdout, "%s\n\n", opts.Description); err != nil {
			return err
		}
	}

	if _, err := fmt.Fprintf(opts.Stdout, "Usage:\n  %s <command> [args]\n\n", opts.BinaryName); err != nil {
		return err
	}
	if _, err := fmt.Fprintln(opts.Stdout, "Commandes communes:"); err != nil {
		return err
	}

	for _, def := range commands {
		if isCommandDisabled(def.Name, opts.DisabledCommands) {
			continue
		}
		if _, err := fmt.Fprintf(opts.Stdout, "  %-7s %s\n", def.Name, def.Description); err != nil {
			return err
		}
	}

	if len(opts.Aliases) > 0 {
		if _, err := fmt.Fprintln(opts.Stdout, "\nAlias:"); err != nil {
			return err
		}

		names := make([]string, 0, len(opts.Aliases))
		for name := range opts.Aliases {
			names = append(names, name)
		}
		sort.Strings(names)

		for _, name := range names {
			target := strings.Join(opts.Aliases[name], " ")
			description := aliasDescription(opts.AliasDescriptions, name, target)
			if _, err := fmt.Fprintf(opts.Stdout, "  %-7s %s\n", name, description); err != nil {
				return err
			}
		}
	}

	if _, err := fmt.Fprintln(opts.Stdout, "\nOptions globales:"); err != nil {
		return err
	}
	if _, err := fmt.Fprintln(opts.Stdout, "  --debug  Active le debug des appels Bitwarden."); err != nil {
		return err
	}

	_, err := fmt.Fprintf(opts.Stdout, "\nAide detaillee: %s help <command>\n", opts.BinaryName)
	return err
}

func autoDisabledCommands(opts Options) []string {
	h := opts.Hooks
	var disabled []string
	if h.Setup == nil {
		disabled = append(disabled, CommandSetup)
	}
	if h.Login == nil {
		disabled = append(disabled, CommandLogin)
	}
	if h.MCP == nil {
		disabled = append(disabled, CommandMCP)
	}
	if h.Config == nil && h.ConfigShow == nil && h.ConfigTest == nil && h.ConfigDelete == nil {
		disabled = append(disabled, CommandConfig)
	}
	if h.Update == nil {
		disabled = append(disabled, CommandUpdate)
	}
	if h.Version == nil && strings.TrimSpace(opts.Version) == "" {
		disabled = append(disabled, CommandVersion)
	}
	return disabled
}

func isCommandDisabled(command string, disabled []string) bool {
	for _, d := range disabled {
		if d == command {
			return true
		}
	}
	return false
}

func aliasDescription(descriptions map[string]string, name, target string) string {
	description := strings.TrimSpace(descriptions[name])
	if description == "" {
		return fmt.Sprintf("Alias de %q.", target)
	}
	return fmt.Sprintf("%s (alias de %q).", description, target)
}