/**
 * Pure rules for ComfyUI-F5-TTS voices (no DOM, no canvas access).
 *
 * F5-TTS multi-voice layout: the node's `sample` is a main voice such as
 * `F5-TTS/Arona.wav`; `{happy}` in the speech loads `F5-TTS/Arona.happy.wav`
 * beside it, and `{main}` is the sample itself. Speech is split only at tags.
 */

export const MAIN_TAG = '{main}';

const normalisePath = value => String(value ?? '').replace(/\\/g, '/');

/** Return the widget's own spelling of `relativePath` (Windows combos use "F5-TTS\\x.wav"), or null when not offered. */
export function comboValueForPath(widget, relativePath) {
    const wanted = normalisePath(relativePath);
    if (!wanted) return null;
    const values = Array.isArray(widget?.options?.values) ? widget.options.values : null;
    if (!values) return wanted;
    return values.find(value => normalisePath(value) === wanted) ?? null;
}

const SENTENCE_END = new Set(['。', '！', '？', '!', '?']);
// Closing quotes/brackets and trailing marks that belong to the sentence they follow.
const TRAILING = new Set(['。', '！', '？', '!', '?', '」', '』', '”', '’', '"', "'", '）', ')', '】', '》', '〉', '~', '～']);
const SPEAKABLE = /[\p{L}\p{N}]/u;

function splitSentences(line) {
    const chars = [...line];
    const segments = [];
    let current = '';
    for (let i = 0; i < chars.length; i++) {
        const char = chars[i];
        current += char;
        // A single '.' ends an English sentence only before whitespace; '3.5', '...' and '……' do not split.
        const isPeriod = char === '.' && chars[i - 1] !== '.' && chars[i + 1] !== '.' && (i + 1 >= chars.length || /\s/.test(chars[i + 1]));
        if (!SENTENCE_END.has(char) && !isPeriod) continue;
        while (i + 1 < chars.length && TRAILING.has(chars[i + 1])) current += chars[++i];
        segments.push(current);
        current = '';
    }
    segments.push(current);
    return segments;
}

/** Punctuation-only pieces ("……", "！」") cannot be spoken on their own: attach them to a neighbour. */
function attachUnspeakable(segments) {
    const result = [];
    let pending = '';
    for (const segment of segments) {
        if (SPEAKABLE.test(segment)) {
            result.push(pending + segment);
            pending = '';
        } else if (result.length) {
            result[result.length - 1] += segment;
        } else {
            pending += segment;
        }
    }
    if (pending) result.push(pending);
    return result;
}

/**
 * Split a script into segments. `sentence`: at 。！？!? (with trailing quotes or
 * brackets) and newlines; ellipses never split. `line`: one segment per line.
 */
export function splitScriptLines(text, mode = 'sentence') {
    const lines = String(text || '').split(/\n+/).map(line => line.trim()).filter(Boolean);
    const segments = mode === 'line' ? lines : lines.flatMap(splitSentences);
    return attachUnspeakable(segments.map(segment => segment.trim()).filter(Boolean));
}

/** Split one segment at a caret position; null when either side would be empty. */
export function splitSegmentAt(text, position) {
    const value = String(text || '');
    const before = value.slice(0, position).trim();
    const after = value.slice(position).trim();
    return before && after ? [before, after] : null;
}

/** Join two segments: a space only between Latin words/digits, none for CJK text. */
export function joinSegments(first, second) {
    const a = String(first || '').trim();
    const b = String(second || '').trim();
    if (!a || !b) return a || b;
    return /[A-Za-z0-9,.;:!?]$/.test(a) && /^[A-Za-z0-9]/.test(b) ? `${a} ${b}` : `${a}${b}`;
}

/** Once any line is tagged, untagged lines get {main} instead of inheriting the previous voice. */
export function composeScript(lines) {
    const anyTagged = lines.some(line => line.voice?.tag);
    return lines
        .map(line => {
            const tag = line.voice?.tag || (anyTagged ? MAIN_TAG : '');
            return tag ? `${tag} ${line.text}` : line.text;
        })
        .join('\n')
        .trim();
}

/** Emotions of a voice group that F5-TTS can load as `{emotion}` (main first). */
export function usableEmotions(group) {
    return (group?.slices || []).filter(slice => slice.tag_usable).map(slice => slice.emotion);
}

/**
 * Bundle script lines for one F5TTSAudio node. `lines` are `{ text, emotion }`;
 * the node's sample becomes the group's main voice and every emotion must be a
 * usable variant of that group. Returns `{ sample, speech, lineCount }` or `{ error: localeKey }`.
 */
export function buildScriptPackage(lines, group) {
    if (!group) return { error: 'scriptDirectorPickCharacter' };
    const usable = new Set(usableEmotions(group));
    if (!group.main_relative_path || !usable.has('main')) return { error: 'scriptDirectorMainMissing' };
    const voiced = [];
    for (const line of lines || []) {
        const text = String(line?.text || '').trim();
        if (!text) continue;
        const emotion = line.emotion || 'main';
        if (!usable.has(emotion)) return { error: 'scriptDirectorVoiceUnusable' };
        voiced.push({ text, voice: emotion === 'main' ? null : { tag: `{${emotion}}` } });
    }
    if (!voiced.length) return { error: 'scriptDirectorEmpty' };
    return { sample: group.main_relative_path, speech: composeScript(voiced), lineCount: voiced.length };
}