package main

import (
	"bytes"
	"context"
	"strings"

	"git.dev.alexdunmow.com/block/core/blocks"
)

// AlphabetStripBlockMeta defines metadata for the alphabet strip block.
var AlphabetStripBlockMeta = blocks.BlockMeta{
	Key:         "alphabet_strip",
	Title:       "Alphabet Strip",
	Description: "Decorative letter band; jumps to anchors when used as TOC.",
	Category:    blocks.CategoryNavigation,
	Source:      "kindergarten",
}

// AlphabetStripData contains the letters + colorway for the rendered strip.
type AlphabetStripData struct {
	Letters   []string
	ColorMode string
}

// AlphabetStripBlock renders a decorative letter band.
// Content shape: {letters,colorMode}.
func AlphabetStripBlock(ctx context.Context, content map[string]any) string {
	raw := getStringDefault(content, "letters", "")
	colorMode := getStringDefault(content, "colorMode", "rainbow")

	// Validate colorMode against allowed set.
	switch colorMode {
	case "primary", "rainbow", "mono":
	default:
		colorMode = "rainbow"
	}

	letters := splitLetters(raw)
	data := AlphabetStripData{
		Letters:   letters,
		ColorMode: colorMode,
	}

	var buf bytes.Buffer
	_ = alphabetStripComponent(data).Render(ctx, &buf)
	return buf.String()
}

// splitLetters returns one entry per visible rune. Whitespace is trimmed.
func splitLetters(s string) []string {
	s = strings.TrimSpace(s)
	if s == "" {
		return nil
	}
	letters := make([]string, 0, len(s))
	for _, r := range s {
		if r == ' ' || r == '\t' || r == '\n' {
			continue
		}
		letters = append(letters, string(r))
	}
	return letters
}