package tgrich

import (
	"fmt"
	"strings"
	"unicode/utf8"

	"git.scuroneko.dev/scuroneko/laniakea/v2/tgapi"
)

func (v *richValidator) button(b tgapi.RichMessageButton, depth int) error {
	actions := 0
	for _, set := range []bool{b.URL != "", b.CallbackData != "", b.WebApp != nil, b.LoginURL != nil, b.SwitchInlineQuery != nil, b.SwitchInlineQueryCurrentChat != nil, b.SwitchInlineQueryChosenChat != nil, b.CopyText != nil, b.Disabled != nil} {
		if set {
			actions++
		}
	}
	if actions != 1 {
		return fmt.Errorf("%w: exactly one action is required", ErrRichInvalidButton)
	}
	switch b.Style {
	case "", "danger", "success", "primary":
	case "link":
		if b.CallbackData == "" {
			return fmt.Errorf("%w: link style requires callback data", ErrRichInvalidButton)
		}
	default:
		return fmt.Errorf("%w: unsupported style", ErrRichInvalidButton)
	}
	if len(b.CallbackData) > 64 {
		return fmt.Errorf("%w: callback data exceeds 64 bytes", ErrRichInvalidButton)
	}
	if b.CopyText != nil && (utf8.RuneCountInString(b.CopyText.Text) < 1 || utf8.RuneCountInString(b.CopyText.Text) > 256) {
		return fmt.Errorf("%w: copy text must contain 1-256 characters", ErrRichInvalidButton)
	}
	if b.LoginURL != nil && b.LoginURL.BotUsername != "" {
		return fmt.Errorf("%w: login bot username is unsupported", ErrRichInvalidButton)
	}
	return v.buttonText(b.Text, depth)
}

func (v *richValidator) buttonText(text tgapi.RichText, depth int) error {
	if depth >= maxRichDepth {
		return ErrRichNestingTooDeep
	}
	switch el := text.(type) {
	case tgapi.RichTextPlain:
		return v.addChars(string(el))
	case tgapi.RichTextCustomEmoji:
		return v.addChars(el.AlternativeText)
	case tgapi.RichTextDateTime:
		return v.buttonText(el.Text, depth+1)
	case tgapi.RichTextArray:
		for _, item := range el {
			if err := v.buttonText(item, depth+1); err != nil {
				return err
			}
		}
		return nil
	default:
		return fmt.Errorf("%w: label allows only plain text, custom emoji, and date-time entities", ErrRichInvalidButton)
	}
}

func renderButton(b tgapi.RichMessageButton, step int) (string, error) {
	if step >= maxRichDepth {
		return "", ErrRichNestingTooDeep
	}
	text, err := renderText(b.Text, step+1)
	if err != nil {
		return "", err
	}
	attrs := map[string]string{}
	if b.Style != "" {
		attrs["style"] = string(b.Style)
	}
	// Empty query values are significant; render them explicitly below.
	var query *string
	switch {
	case b.URL != "":
		attrs["type"], attrs["url"] = "url", b.URL
	case b.CallbackData != "":
		attrs["type"], attrs["data"] = "callback_data", b.CallbackData
	case b.WebApp != nil:
		attrs["type"], attrs["url"] = "web_app", b.WebApp.URL
	case b.LoginURL != nil:
		attrs["type"], attrs["url"] = "login_url", b.LoginURL.URL
		if b.LoginURL.ForwardText != "" {
			attrs["forward-text"] = b.LoginURL.ForwardText
		}
		if b.LoginURL.RequestWriteAccess {
			attrs["request-write-access"] = ""
		}
	case b.SwitchInlineQuery != nil:
		attrs["type"], query = "switch_inline_query", b.SwitchInlineQuery
	case b.SwitchInlineQueryCurrentChat != nil:
		attrs["type"], query = "switch_inline_query_current_chat", b.SwitchInlineQueryCurrentChat
	case b.SwitchInlineQueryChosenChat != nil:
		c := b.SwitchInlineQueryChosenChat
		attrs["type"], query = "switch_inline_query_chosen_chat", &c.Query
		for key, enabled := range map[string]bool{"allow-user-chats": c.AllowUserChats, "allow-bot-chats": c.AllowBotChats, "allow-group-chats": c.AllowGroupChats, "allow-channel-chats": c.AllowChannelChats} {
			if enabled {
				attrs[key] = ""
			}
		}
	case b.CopyText != nil:
		attrs["type"], attrs["text"] = "copy_text", b.CopyText.Text
	case b.Disabled != nil:
		attrs["type"] = "disabled"
	default:
		return "", ErrRichInvalidButton
	}
	formatted := formatAttrs(attrs)
	if query != nil {
		formatted = append(formatted, `query="`+escapeHTML(*query)+`"`)
	}
	return openTag("tg-button", formatted) + text + "</tg-button>", nil
}

func renderButtons(row tgapi.InputRichBlockButtons, step int) (string, error) {
	var content strings.Builder
	for _, button := range row.Buttons {
		html, err := renderButton(button, step+1)
		if err != nil {
			return "", err
		}
		content.WriteString(html)
	}
	attrs := map[string]string{}
	if row.Align != "" {
		attrs["align"] = string(row.Align)
	}
	return openTag("tg-button-row", formatAttrs(attrs)) + content.String() + "</tg-button-row>", nil
}