package control

import (
	"context"
	"fmt"
	"strconv"
	"strings"

	"reasonix/internal/config"
	"reasonix/internal/i18n"
	"reasonix/internal/migration"
	"reasonix/internal/pluginpkg"
	"reasonix/internal/skill"
)

// SlashItem is one slash-completion suggestion. Insert is the token text placed
// at the current argument position (callers replace from the token's start, see
// SlashArgItems' returned offset); Descend hints the menu to re-open one level
// deeper after accepting (e.g. "/mcp " → "/mcp add ").
type SlashItem struct {
	Label   string `json:"label"`
	Insert  string `json:"insert"`
	Hint    string `json:"hint"`
	Descend bool   `json:"descend"`
}

// ArgData supplies the dynamic data SlashArgItems needs, so the completion logic
// is one shared function both frontends call with their own session data — the
// chat TUI (controller-free, from its cached lists) and the desktop (from the
// controller). This keeps the CLI and desktop sub-command hints identical.
type ArgData struct {
	Skills          []skill.Skill
	DisabledSkills  []skill.Skill
	ServerNames     []string
	ConfiguredMCP   []string
	DisconnectedMCP []string
	ModelRefs       []string
	CurrentModel    string
	ProviderNames   []string
	CurrentProvider string
	PluginNames     []string
	MemoryRefs      []string
	MemoryArchives  []string
}

// SlashArgItems completes the arguments of a management slash command
// (everything after the command word). It returns the suggestions filtered by
// the token being typed and the byte offset where that token begins, so a caller
// replaces just that token. Only structured commands participate (/mcp /model
// /skills /plugins /hooks /effort /goal /reasoning-language
// /theme /language /currency /memory);
// others yield nil. Single source of truth for CLI + desktop.
func SlashArgItems(line string, d ArgData) ([]SlashItem, int) {
	cmdEnd := strings.IndexAny(line, " \t")
	if cmdEnd < 0 {
		return nil, 0
	}
	from := strings.LastIndexAny(line, " \t") + 1
	cur := line[from:]
	prior := strings.Fields(line[:from]) // committed tokens, including the command word
	var raw []SlashItem
	switch line[:cmdEnd] {
	case "/mcp":
		raw = mcpArgItems(prior, cur, d)
	case "/model":
		raw = modelArgItems(prior, d)
	case "/provider":
		raw = providerArgItems(prior, d)
	case "/skill", "/skills":
		raw = skillArgItems(prior, d)
	case "/plugin", "/plugins":
		raw = pluginArgItems(prior, d)
	case "/hooks":
		raw = hooksArgItems(prior)
	case "/effort":
		raw = effortArgItems(prior, d)
	case "/goal":
		raw = goalArgItems(prior)
	case "/reasoning-language":
		raw = reasoningLanguageArgItems(prior)
	case "/theme":
		raw = themeArgItems(prior)
	case "/language":
		raw = languageArgItems(prior)
	case "/currency":
		raw = currencyArgItems(prior)
	case "/memory":
		raw = memoryArgItems(prior, d)
	default:
		return nil, from
	}
	return filterSlash(raw, line, from, cur), from
}

func memoryArgItems(prior []string, d ArgData) []SlashItem {
	if len(prior) <= 1 {
		return []SlashItem{
			{Label: "recall", Insert: "recall", Hint: "show the latest automatic recall decision"},
			{Label: "revisions", Insert: "revisions ", Hint: "show revision history", Descend: true},
			{Label: "restore", Insert: "restore ", Hint: "restore an older revision", Descend: true},
			{Label: "archived", Insert: "archived", Hint: "show archived facts"},
			{Label: "recover", Insert: "recover ", Hint: "recover an archived fact", Descend: true},
			{Label: "instructions", Insert: "instructions", Hint: "show precedence, imports, and diagnostics"},
		}
	}
	switch prior[1] {
	case "revisions", "restore":
		if len(prior) != 2 {
			return nil
		}
		items := make([]SlashItem, 0, len(d.MemoryRefs))
		for _, ref := range d.MemoryRefs {
			items = append(items, SlashItem{Label: ref, Insert: ref})
		}
		return items
	case "recover":
		if len(prior) != 2 {
			return nil
		}
		items := make([]SlashItem, 0, len(d.MemoryArchives))
		for _, path := range d.MemoryArchives {
			items = append(items, SlashItem{Label: path, Insert: `"` + path + `"`})
		}
		return items
	}
	return nil
}

func goalArgItems(prior []string) []SlashItem {
	if len(prior) > 1 {
		return nil
	}
	return []SlashItem{
		{Label: "status", Insert: "status", Hint: "show active goal and budget runtime"},
		{Label: "pause", Insert: "pause", Hint: "pause the running goal (keeps all state)"},
		{Label: "resume", Insert: "resume", Hint: "resume a paused goal (adds one turn slice)"},
		{Label: "clear", Insert: "clear", Hint: "stop goal mode"},
	}
}

func reasoningLanguageArgItems(prior []string) []SlashItem {
	if len(prior) > 1 {
		return nil
	}
	return []SlashItem{
		{Label: "auto", Insert: "auto", Hint: "follow conversation language"},
		{Label: "zh", Insert: "zh", Hint: "prefer Chinese visible reasoning"},
		{Label: "en", Insert: "en", Hint: "prefer English visible reasoning"},
	}
}

func languageArgItems(prior []string) []SlashItem {
	if len(prior) > 1 {
		return nil
	}
	return []SlashItem{
		{Label: "auto", Insert: "auto", Hint: i18n.M.ArgLanguageAuto},
		{Label: "en", Insert: "en", Hint: i18n.M.ArgLanguageEn},
		{Label: "zh", Insert: "zh", Hint: i18n.M.ArgLanguageZh},
	}
}

func currencyArgItems(prior []string) []SlashItem {
	if len(prior) != 1 {
		return nil
	}
	return []SlashItem{
		{Label: "auto", Insert: "auto", Hint: "follow the resolved CLI locale"},
		{Label: "CNY", Insert: "CNY", Hint: "Chinese yuan pricing"},
		{Label: "USD", Insert: "USD", Hint: "US dollar pricing"},
	}
}

func themeArgItems(prior []string) []SlashItem {
	if len(prior) > 1 {
		return nil
	}
	items := []SlashItem{
		{Label: "auto", Insert: "auto", Hint: "mode · detect system or terminal background"},
		{Label: "light", Insert: "light", Hint: "mode · force light shell"},
		{Label: "dark", Insert: "dark", Hint: "mode · force dark shell"},
	}
	for _, st := range []struct {
		name string
		mode string
		desc string
	}{
		{"graphite", "dark", "warm clay accent"},
		{"ember", "dark", "hot orange accent"},
		{"aurora", "dark", "cool teal accent"},
		{"midnight", "dark", "quiet violet accent"},
		{"sandstone", "light", "default warm light accent"},
		{"porcelain", "light", "soft violet light accent"},
		{"linen", "light", "muted coral light accent"},
		{"glacier", "light", "cool blue accent"},
	} {
		items = append(items, SlashItem{Label: st.name, Insert: st.name, Hint: st.mode + " · " + st.desc})
	}
	return items
}

func effortArgItems(prior []string, d ArgData) []SlashItem {
	if len(prior) <= 1 {
		entry := currentEffortEntry(d)
		cap := config.EffortCapabilityForEntry(entry)
		var out []SlashItem
		for _, level := range cap.Levels {
			hint := ""
			switch level {
			case "auto":
				hint = i18n.M.ArgEffortAuto
			case "low":
				hint = i18n.M.ArgEffortLow
			case "medium":
				hint = i18n.M.ArgEffortMedium
			case "high":
				hint = i18n.M.ArgEffortHigh
			case "xhigh":
				hint = i18n.M.ArgEffortXHigh
			case "max":
				hint = i18n.M.ArgEffortMax
			}
			out = append(out, SlashItem{Label: level, Insert: level, Hint: hint})
		}
		return out
	}
	return nil
}

func currentEffortEntry(d ArgData) *config.ProviderEntry {
	if strings.TrimSpace(d.CurrentModel) == "" {
		return nil
	}
	cfg, err := config.Load()
	if err != nil {
		return nil
	}
	entry, _ := cfg.ResolveModel(d.CurrentModel)
	return entry
}

func mcpArgItems(prior []string, cur string, d ArgData) []SlashItem {
	if len(prior) <= 1 {
		return []SlashItem{
			{Label: "add", Insert: "add ", Hint: i18n.M.ArgMcpAdd, Descend: true},
			{Label: "connect", Insert: "connect ", Hint: "connect a configured MCP server", Descend: true},
			{Label: "show", Insert: "show ", Hint: "show MCP server details", Descend: true},
			{Label: "tools", Insert: "tools ", Hint: "show MCP server tools", Descend: true},
			{Label: "remove", Insert: "remove ", Hint: i18n.M.ArgMcpRemove, Descend: true},
			{Label: "import", Insert: "import", Hint: "import MCP servers from cc-switch"},
		}
	}
	switch prior[1] {
	case "remove", "rm":
		if len(prior) != 2 { // the single name arg is already placed
			return nil
		}
		var items []SlashItem
		for _, name := range d.ServerNames {
			items = append(items, SlashItem{Label: name, Insert: name, Hint: i18n.M.ArgMcpConnected})
		}
		return items
	case "show", "tools":
		if len(prior) != 2 {
			return nil
		}
		var items []SlashItem
		for _, name := range allMCPArgNames(d) {
			items = append(items, SlashItem{Label: name, Insert: name})
		}
		return items
	case "connect":
		if len(prior) != 2 {
			return nil
		}
		var items []SlashItem
		for _, name := range d.DisconnectedMCP {
			items = append(items, SlashItem{Label: name, Insert: name, Hint: "configured"})
		}
		return items
	case "add":
		if strings.HasPrefix(cur, "-") {
			return []SlashItem{
				{Label: "--http", Insert: "--http ", Hint: "Streamable HTTP URL"},
				{Label: "--sse", Insert: "--sse ", Hint: "legacy SSE URL"},
				{Label: "--env", Insert: "--env ", Hint: "KEY=VALUE (stdio)"},
				{Label: "--header", Insert: "--header ", Hint: "KEY=VALUE (remote)"},
			}
		}
	}
	return nil
}

func allMCPArgNames(d ArgData) []string {
	seen := map[string]bool{}
	var out []string
	for _, list := range [][]string{d.ServerNames, d.ConfiguredMCP, d.DisconnectedMCP} {
		for _, name := range list {
			if strings.TrimSpace(name) == "" || seen[name] {
				continue
			}
			seen[name] = true
			out = append(out, name)
		}
	}
	return out
}

func modelArgItems(prior []string, d ArgData) []SlashItem {
	if len(prior) != 1 { // the single ref arg is already placed
		return nil
	}
	var items []SlashItem
	for _, ref := range d.ModelRefs {
		hint := ""
		if ref == d.CurrentModel {
			hint = i18n.M.ArgModelCurrent
		}
		items = append(items, SlashItem{Label: ref, Insert: ref, Hint: hint})
	}
	return items
}

func providerArgItems(prior []string, d ArgData) []SlashItem {
	if len(prior) != 1 { // the single name arg is already placed
		return nil
	}
	var items []SlashItem
	for _, name := range d.ProviderNames {
		hint := ""
		if name == d.CurrentProvider {
			hint = i18n.M.ArgModelCurrent
		}
		items = append(items, SlashItem{Label: name, Insert: name, Hint: hint})
	}
	return items
}

func skillArgItems(prior []string, d ArgData) []SlashItem {
	if len(prior) <= 1 {
		return []SlashItem{
			{Label: "show", Insert: "show ", Hint: i18n.M.ArgSkillShow, Descend: true},
			{Label: "enable", Insert: "enable ", Hint: "enable a disabled skill", Descend: true},
			{Label: "disable", Insert: "disable ", Hint: "disable an enabled skill", Descend: true},
			{Label: "new", Insert: "new ", Hint: i18n.M.ArgSkillNew},
			{Label: "paths", Insert: "paths", Hint: i18n.M.ArgSkillPaths},
		}
	}
	if (prior[1] == "show" || prior[1] == "cat") && len(prior) == 2 {
		var items []SlashItem
		for _, s := range d.Skills {
			items = append(items, SlashItem{Label: s.Name, Insert: s.Name, Hint: string(s.Scope)})
		}
		return items
	}
	if prior[1] == "disable" && len(prior) == 2 {
		var items []SlashItem
		for _, s := range d.Skills {
			items = append(items, SlashItem{Label: s.Name, Insert: s.Name, Hint: string(s.Scope)})
		}
		return items
	}
	if prior[1] == "enable" && len(prior) == 2 {
		var items []SlashItem
		for _, s := range d.DisabledSkills {
			items = append(items, SlashItem{Label: s.Name, Insert: s.Name, Hint: string(s.Scope)})
		}
		return items
	}
	return nil
}

func pluginArgItems(prior []string, d ArgData) []SlashItem {
	if len(prior) <= 1 {
		return []SlashItem{
			{Label: "show", Insert: "show ", Hint: "show plugin capabilities and usage", Descend: true},
		}
	}
	if (prior[1] == "show" || prior[1] == "cat") && len(prior) == 2 {
		var items []SlashItem
		for _, name := range d.PluginNames {
			items = append(items, SlashItem{Label: name, Insert: name})
		}
		return items
	}
	return nil
}

func hooksArgItems(prior []string) []SlashItem {
	if len(prior) <= 1 {
		return []SlashItem{
			{Label: "list", Insert: "list", Hint: i18n.M.ArgHooksList},
		}
	}
	return nil
}

// filterSlash keeps items whose label starts with the typed token (case-
// insensitive) and drops no-op suggestions — ones whose insert wouldn't change
// the line because the token is already fully typed (e.g. "/skills list" offering
// "list"). Without this the menu lingers on a complete command and Enter keeps
// "accepting" the no-op instead of sending.
func filterSlash(items []SlashItem, line string, from int, cur string) []SlashItem {
	lp := strings.ToLower(cur)
	prefix := line[:from]
	var out []SlashItem
	for _, it := range items {
		if !strings.HasPrefix(strings.ToLower(it.Label), lp) {
			continue
		}
		if prefix+it.Insert == line {
			continue // token already complete: nothing to add
		}
		out = append(out, it)
	}
	return out
}

// managementNotice handles management slash commands on the Submit path (used by
// the desktop and HTTP frontends, which route raw input through Submit — the chat
// TUI has its own richer handlers). It emits Notice output and reports whether
// it handled the verb. Skills and custom commands are NOT here — those resolve
// to a turn in Submit.
func (c *Controller) managementNotice(trimmed string) bool {
	fields := strings.Fields(trimmed)
	if len(fields) == 0 {
		return false
	}
	switch fields[0] {
	case "/model":
		c.notice(c.modelListText())
	case "/provider":
		if len(fields) >= 2 {
			c.notice(c.providerSwitchText(fields[1]))
		} else {
			c.notice(c.providerListText())
		}
	case "/memory":
		args := strings.TrimSpace(strings.TrimPrefix(trimmed, fields[0]))
		c.notice(MemoryCommandText(c, args))
	case "/migrate", "/migration":
		args := strings.TrimSpace(strings.TrimPrefix(trimmed, fields[0]))
		migration.RunLegacyRescueCommand(args, c.sink)
	case "/skill", "/skills":
		sub := ""
		if len(fields) >= 2 {
			sub = strings.ToLower(fields[1])
		}
		if len(fields) >= 3 && (sub == "enable" || sub == "disable") {
			enabled := sub == "enable"
			if err := c.SetSkillEnabled(fields[2], enabled); err != nil {
				c.notice("skill " + sub + ": " + err.Error())
			} else if enabled {
				c.notice("enabled skill " + fields[2] + " — restart or refresh the session for the prompt and tools to update")
			} else {
				c.notice("disabled skill " + fields[2] + " — restart or refresh the session for the prompt and tools to update")
			}
			return true
		}
		c.notice(c.skillListText())
	case "/plugin", "/plugins":
		sub := ""
		if len(fields) >= 2 {
			sub = strings.ToLower(fields[1])
		}
		switch sub {
		case "", "list", "ls":
			text, err := pluginpkg.InstalledListText(config.ReasonixHomeDir())
			if err != nil {
				c.notice("plugins: " + err.Error())
			} else {
				c.notice(text)
			}
		case "show", "cat":
			if len(fields) < 3 {
				c.notice("usage: /plugins show <name>")
				return true
			}
			text, err := pluginpkg.InstalledShowText(config.ReasonixHomeDir(), fields[2])
			if err != nil {
				c.notice("plugins: " + err.Error())
			} else {
				c.notice(text)
			}
		default:
			c.notice("unknown /plugins subcommand " + fields[1] + " - try: /plugins or /plugins show <name>")
		}
	case "/reload-cmd":
		if c.Running() {
			c.notice("wait for the current turn to finish, then retry /reload-cmd")
			return true
		}
		if err := c.ReloadCommands(context.Background()); err != nil {
			c.notice("reload-cmd: " + err.Error())
		} else {
			visible := 0
			for _, cmd := range c.Commands() {
				if !cmd.Hidden {
					visible++
				}
			}
			c.notice("commands reloaded (" + strconv.Itoa(visible) + " available)")
		}
	case "/hooks":
		sub := ""
		if len(fields) >= 2 {
			sub = strings.ToLower(fields[1])
		}
		switch sub {
		case "", "list", "ls":
			c.notice(c.hookListText())
		case "trust":
			// Backward-compatible response for old clients and saved commands.
			c.notice("project hooks are enabled automatically; no trust action is required")
		default:
			c.notice("unknown /hooks subcommand " + fields[1] + " — try: /hooks or /hooks list")
		}
	case "/mcp":
		if len(fields) >= 3 && fields[1] == "connect" {
			n, err := c.ConnectConfiguredMCPServer(fields[2])
			if err != nil {
				c.notice("mcp connect: " + err.Error())
			} else {
				c.notice(fmt.Sprintf("connected %s — %d tools", fields[2], n))
			}
			return true
		}
		c.notice(c.mcpListText())
	default:
		return false
	}
	return true
}

func (c *Controller) modelListText() string {
	cfg, err := config.Load()
	if err != nil {
		return "model: " + err.Error()
	}
	var b strings.Builder
	fmt.Fprintf(&b, i18n.M.ListModelsHeaderFmt+"\n", c.label)
	for i := range cfg.Providers {
		p := &cfg.Providers[i]
		if !p.Configured() {
			continue
		}
		for _, m := range p.ChatModelList() {
			fmt.Fprintf(&b, "  %s/%s\n", p.Name, m)
		}
	}
	b.WriteString(i18n.M.ListModelsHint)
	return strings.TrimRight(b.String(), "\n")
}

func (c *Controller) providerListText() string {
	cfg, err := config.Load()
	if err != nil {
		return "provider: " + err.Error()
	}
	curProvider := ""
	if parts := strings.Fields(c.label); len(parts) > 0 {
		curProvider = parts[0]
	}
	var b strings.Builder
	b.WriteString(i18n.M.ProviderListHeader + "\n")
	for i := range cfg.Providers {
		p := &cfg.Providers[i]
		if !p.Configured() {
			continue
		}
		models := p.ChatModelList()
		if len(models) == 0 {
			models = p.ModelList()
		}
		suffix := ""
		if p.Name == curProvider {
			suffix = " (active)"
		}
		fmt.Fprintf(&b, "  %s — %d models%s\n", p.Name, len(models), suffix)
	}
	b.WriteString("switch with /provider <name>")
	return strings.TrimRight(b.String(), "\n")
}

func (c *Controller) providerSwitchText(name string) string {
	cfg, err := config.Load()
	if err != nil {
		return "provider: " + err.Error()
	}
	for i := range cfg.Providers {
		p := &cfg.Providers[i]
		if p.Name == name && p.Configured() {
			models := p.ChatModelList()
			if len(models) == 0 {
				models = p.ModelList()
			}
			if len(models) == 0 {
				return fmt.Sprintf(i18n.M.ProviderNoModelsFmt, name)
			}
			if len(models) == 1 {
				return fmt.Sprintf("provider %s — model: %s (switch with /model %s/%s)", name, models[0], name, models[0])
			}
			var b strings.Builder
			fmt.Fprintf(&b, "provider %s — %d models:\n", name, len(models))
			for _, m := range models {
				fmt.Fprintf(&b, "  %s/%s\n", name, m)
			}
			fmt.Fprintf(&b, "switch with /model %s/<model>", name)
			return strings.TrimRight(b.String(), "\n")
		}
	}
	return fmt.Sprintf(i18n.M.ProviderUnknownFmt, name)
}

func (c *Controller) skillListText() string {
	skills := c.skills.discovered()
	if len(skills) == 0 {
		return i18n.M.ListSkillsNone
	}
	var b strings.Builder
	fmt.Fprintf(&b, i18n.M.ListSkillsHeaderFmt+"\n", len(skills))
	for _, s := range skills {
		tag := ""
		if s.RunAs == "subagent" {
			tag = " 🧬"
		}
		fmt.Fprintf(&b, "  /%s%s — %s\n", s.Name, tag, s.Description)
	}
	return strings.TrimRight(b.String(), "\n")
}

func (c *Controller) hookListText() string {
	hooks := c.hooks.Hooks()
	if len(hooks) == 0 {
		return i18n.M.ListHooksNone
	}
	var b strings.Builder
	fmt.Fprintf(&b, i18n.M.ListHooksHeaderFmt+"\n", len(hooks))
	for _, h := range hooks {
		match := h.Match
		if match == "" {
			match = "*"
		}
		fmt.Fprintf(&b, "  %s [%s] %s — %s\n", h.Event, h.Scope, match, h.Command)
	}
	return strings.TrimRight(b.String(), "\n")
}

func (c *Controller) mcpListText() string {
	names := c.mcp.serverNames()
	if len(names) == 0 && len(c.mcp.failures()) == 0 {
		return i18n.M.ListMcpNone
	}
	var b strings.Builder
	if len(names) > 0 {
		b.WriteString(i18n.M.ListMcpHeader + "\n")
		for _, name := range names {
			fmt.Fprintf(&b, "  %s\n", name)
		}
	}
	if failures := c.mcp.failures(); len(failures) > 0 {
		if b.Len() > 0 {
			b.WriteString("\n")
		}
		b.WriteString("MCP startup failures:\n")
		for _, f := range failures {
			fmt.Fprintf(&b, "  %s (%s): %s\n", f.Name, f.Transport, f.Error)
		}
	}
	return strings.TrimRight(b.String(), "\n")
}