/**
 * Book Pagination Module
 * Converts story blocks into texture-space page lines for the WebGL book.
 */
import { BaseModule } from './base-module.js';

class BookPaginationModule extends BaseModule {
    constructor() {
        super('book-pagination', 'Book Pagination');
        this.dependencies = ['book-page-format', 'paragraph-layout', 'story-history'];
        this.pageFormat = null;
        this.paragraphLayout = null;
        this.storyHistory = null;
        this.metrics = null;
        this.spreads = [];
        this.currentSpreadIndex = 0;
        this.refreshToken = 0;
        this.latestBlockId = 0;
        this.latestRenderedBlockId = 0;

        this.bindMethods([
            'initialize',
            'refreshFromHistory',
            'buildSpreads',
            'layoutTextBlock',
            'getDropCapText',
            'extractDropCapText',
            'measureDropCapReservation',
            'measureNormalTextGap',
            'calculateDropCapLayout',
            'extractLayoutLine',
            'extractRemainingLayoutText',
            'extractLines',
            'countLineWords',
            'getLineGeometry',
            'getSpread',
            'getCurrentSpread',
            'setCurrentSpread',
            'publish'
        ]);
    }

    async initialize() {
        this.pageFormat = this.getModule('book-page-format');
        this.paragraphLayout = this.getModule('paragraph-layout');
        this.storyHistory = this.getModule('story-history');
        this.metrics = this.pageFormat.getTextureMetrics(1280);

        this.reportProgress(35, 'Preparing book pagination metrics');
        this.addEventListener(document, 'story:history-updated', this.refreshFromHistory);
        this.addEventListener(document, 'book-pagination:set-spread', (event) => {
            this.setCurrentSpread(event.detail?.spreadIndex);
        });
        this.reportProgress(100, 'Book pagination ready');
        return true;
    }

    async refreshFromHistory(event = null) {
        const token = ++this.refreshToken;
        const detail = event?.detail || {};
        const gameId = detail.gameId || this.storyHistory?.currentGameId || null;
        const latestBlockId = Math.max(
            0,
            Number(detail.latestRenderedBlockId || detail.latestBlockId || this.storyHistory?.latestRenderedBlockId || (this.storyHistory?.nextBlockId || 1) - 1)
        );
        if (!gameId || latestBlockId <= 0 || typeof this.storyHistory?.getBlocksRange !== 'function') {
            this.spreads = [];
            this.latestBlockId = 0;
            this.latestRenderedBlockId = 0;
            this.publish();
            return;
        }

        const blocks = await this.storyHistory.getBlocksRange(gameId, 1, latestBlockId);
        if (token !== this.refreshToken) return;
        this.latestBlockId = latestBlockId;
        this.latestRenderedBlockId = Math.max(
            0,
            Number(detail.latestRenderedBlockId || this.storyHistory?.latestRenderedBlockId || 0)
        );
        this.spreads = this.buildSpreads(blocks);
        this.currentSpreadIndex = Math.max(0, Math.min(this.currentSpreadIndex, Math.max(0, this.spreads.length - 1)));
        this.publish();
    }

    buildSpreads(blocks = []) {
        const spreads = [];
        let cursorLine = 0;
        const source = Array.isArray(blocks) ? blocks : [];

        source.forEach((block) => {
            const type = block?.kind || block?.type || 'paragraph';
            if (!['paragraph', 'heading'].includes(type)) return;

            const layout = this.layoutTextBlock(block, type);
            if (!layout?.lines?.length) return;
            let blockWordCursor = 0;
            cursorLine += layout.topSpaceLines;

            layout.lines.forEach((line, layoutLineIndex) => {
                const geometry = this.getLineGeometry(cursorLine);
                const lineWordCount = this.countLineWords(line);
                if (!spreads[geometry.spreadIndex]) {
                    spreads[geometry.spreadIndex] = { index: geometry.spreadIndex, left: [], right: [] };
                }
                spreads[geometry.spreadIndex][geometry.side].push({
                    blockId: block.blockId ?? null,
                    turnId: block.turnId ?? block.metadata?.turnId ?? null,
                    role: layout.role,
                    text: block.text || '',
                    line,
                    lineIndex: cursorLine,
                    pageLine: geometry.pageLine,
                    fontPx: layout.fontPx,
                    lineHeightPx: layout.lineHeightPx,
                    fontStyle: layout.fontStyle,
                    blockWordStart: blockWordCursor,
                    dropCapText: layoutLineIndex === 0 ? layout.dropCapText : '',
                    smallCaps: Boolean(layout.dropCap && layoutLineIndex === 0)
                });
                blockWordCursor += lineWordCount;
                cursorLine += 1;
            });
            cursorLine += layout.bottomSpaceLines;
        });

        return spreads.filter(Boolean);
    }

    layoutTextBlock(block = {}, type = 'paragraph') {
        const sourceText = String(block.layoutText || block.text || '').trim();
        const dropCap = Boolean(block.dropCap || block.metadata?.dropCap);
        const dropCapText = dropCap ? this.getDropCapText(sourceText) : '';
        const text = dropCap ? this.extractDropCapText(sourceText) : sourceText;
        if (!text || !this.paragraphLayout) return null;

        const typography = this.metrics.typography;
        const role = block.role || block.metadata?.role || (type === 'heading' ? 'chapter-heading' : 'body');
        const isHeading = type === 'heading' || role === 'chapter-heading' || role === 'section-heading';
        const topSpaceLines = role === 'chapter-heading' ? 2 : role === 'section-heading' || block.addTopSpace || block.metadata?.addTopSpace ? 1 : 0;
        const bottomSpaceLines = role === 'chapter-heading' || role === 'section-heading' ? 1 : 0;
        const lineHeightPx = Math.max(1, Number(this.metrics.typographyLineHeightPx || 1));
        const fontPx = Math.max(1, Number(this.metrics.bodyFontSizePx || lineHeightPx / 1.5));
        const dropCapWidth = dropCap ? this.measureDropCapReservation(dropCapText, fontPx, lineHeightPx) : 0;
        const indent = (isHeading || block.isFirstParagraphInChapter || block.metadata?.isFirstParagraphInChapter || block.addTopSpace)
            ? 0
            : lineHeightPx * 1.5;
        const measures = isHeading
            ? [this.metrics.content.width]
            : dropCap
                ? [Math.max(120, this.metrics.content.width - dropCapWidth), Math.max(120, this.metrics.content.width - dropCapWidth), this.metrics.content.width]
                : [Math.max(120, this.metrics.content.width - indent), this.metrics.content.width, this.metrics.content.width];
        const lineOffsets = isHeading ? [0] : dropCap ? [dropCapWidth, dropCapWidth, 0] : [indent, 0, 0];

        const layoutOptions = {
            measures,
            fontSize: `${fontPx}px`,
            fontFamily: typography.fontFamily,
            fontFeatureSettings: '"kern" on, "liga" on, "onum" on, "pnum" on, "dlig" on, "clig" on, "calt" on',
            lineHeightPx,
            lineHeight: lineHeightPx / fontPx
        };
        const layout = dropCap
            ? this.calculateDropCapLayout(text, measures, lineOffsets, layoutOptions)
            : this.paragraphLayout.calculateLayout(text, layoutOptions);
        if (!layout) return null;

        return {
            role,
            fontPx,
            lineHeightPx,
            fontStyle: isHeading ? 'italic' : 'normal',
            topSpaceLines,
            bottomSpaceLines,
            dropCapText,
            dropCap,
            lines: this.extractLines(layout, {
                measures,
                lineOffsets,
                align: isHeading ? 'center' : 'justify'
            })
        };
    }

    getDropCapText(text) {
        return String(text || '').trimStart().match(/\S/u)?.[0] || '';
    }

    extractDropCapText(text) {
        const dropCap = this.getDropCapText(text);
        if (!dropCap) return String(text || '');
        return String(text || '').replace(dropCap, '').trimStart();
    }

    measureDropCapReservation(dropCapText, fontPx, lineHeightPx) {
        if (!dropCapText) return lineHeightPx * 1.34;
        const canvas = document.createElement('canvas');
        const context = canvas.getContext('2d');
        if (!context) return lineHeightPx * 1.34;

        const dropCapFontPx = Math.round(fontPx * 2.68);
        context.font = `${dropCapFontPx}px "EB Garamond Initials", ${this.metrics.typography.fontFamily}`;
        const metrics = context.measureText(dropCapText);
        const inkRight = Number.isFinite(metrics.actualBoundingBoxRight) && metrics.actualBoundingBoxRight > 0
            ? metrics.actualBoundingBoxRight
            : (metrics.width || 0);
        return Math.max(inkRight, lineHeightPx * 1.08) + this.measureNormalTextGap(fontPx);
    }

    measureNormalTextGap(fontPx) {
        const canvas = document.createElement('canvas');
        const context = canvas.getContext('2d');
        if (!context) return fontPx * 0.75;
        context.font = `${fontPx}px ${this.metrics.typography.fontFamily}`;
        const gap = context.measureText('\u2002').width;
        return Number.isFinite(gap) && gap > 0 ? gap : fontPx * 0.75;
    }

    calculateDropCapLayout(text, measures, lineOffsets, layoutOptions) {
        const firstLineOptions = {
            ...layoutOptions,
            measures: [measures[0], Math.max(measures[0] * 20, 10000)],
            fontVariantCaps: 'all-small-caps',
            fontFeatureSettings: '"smcp" on, "c2sc" on, "kern" on, "liga" on, "onum" on, "pnum" on'
        };
        const firstLayout = this.paragraphLayout.calculateLayout(text, firstLineOptions);
        if (!firstLayout?.breaks || firstLayout.breaks.length < 2) {
            return this.paragraphLayout.calculateLayout(text, layoutOptions);
        }

        const firstLine = this.extractLayoutLine(firstLayout, 0, {
            measure: measures[0],
            offset: lineOffsets[0],
            smallCaps: true
        });
        const remainingText = this.extractRemainingLayoutText(firstLayout, firstLayout.breaks[1].position);
        const remainingLayout = this.paragraphLayout.calculateLayout(remainingText, {
            ...layoutOptions,
            measures: [measures[1], ...measures.slice(2)]
        });
        const remainingLines = [];
        if (remainingLayout?.breaks?.length > 1) {
            for (let lineIndex = 0; lineIndex < remainingLayout.breaks.length - 1; lineIndex += 1) {
                remainingLines.push(this.extractLayoutLine(remainingLayout, lineIndex, {
                    measure: measures[Math.min(lineIndex + 1, measures.length - 1)],
                    offset: lineOffsets[Math.min(lineIndex + 1, lineOffsets.length - 1)] || 0,
                    smallCaps: false
                }));
            }
        }

        return {
            lines: [firstLine, ...remainingLines].filter(Boolean),
            processedText: text,
            lineHeight: layoutOptions.lineHeight,
            lineHeightPx: layoutOptions.lineHeightPx,
            fontSize: layoutOptions.fontSize,
            fontFamily: layoutOptions.fontFamily
        };
    }

    extractLayoutLine(layout, lineIndex, metadata = {}) {
        const startBreak = layout.breaks?.[lineIndex];
        const endBreak = layout.breaks?.[lineIndex + 1];
        if (!startBreak || !endBreak || !Array.isArray(layout.nodes)) return null;
        const nodes = [];
        for (let index = startBreak.position; index <= endBreak.position; index += 1) {
            const node = layout.nodes[index];
            if (!node) continue;
            if (node.type === 'glue' && (index === startBreak.position || index === endBreak.position)) continue;
            const forcedBreak = window.linebreak?.infinity ? -window.linebreak.infinity : -100000;
            if (node.type === 'penalty' && node.penalty <= forcedBreak) continue;
            nodes.push({ ...node });
        }
        const endNode = layout.nodes[endBreak.position];
        return {
            nodes,
            measure: metadata.measure,
            offset: metadata.offset || 0,
            ratio: endBreak.ratio || 0,
            isFinal: lineIndex === layout.breaks.length - 2,
            smallCaps: Boolean(metadata.smallCaps),
            hyphenated: Boolean(endNode?.type === 'penalty' && endNode.penalty === 100),
            align: 'justify'
        };
    }

    extractRemainingLayoutText(layout, breakPosition) {
        if (!Array.isArray(layout.nodes)) return '';
        const fragments = [];
        for (let index = breakPosition + 1; index < layout.nodes.length; index += 1) {
            const node = layout.nodes[index];
            if (!node) continue;
            if (node.type === 'box' || node.type === 'tag') {
                fragments.push(node.value || '');
            } else if (node.type === 'glue' && node.width > 0) {
                fragments.push(' ');
            } else if (node.type === 'penalty' && node.penalty === 100) {
                fragments.push('|');
            }
        }
        return fragments.join('').replace(/\s+/g, ' ').trimStart();
    }

    extractLines(layout, options = {}) {
        if (Array.isArray(layout?.lines)) return layout.lines;
        const lines = [];
        const breaks = Array.isArray(layout.breaks) ? layout.breaks : [];
        const nodes = Array.isArray(layout.nodes) ? layout.nodes : [];
        for (let index = 1; index < breaks.length; index += 1) {
            const start = breaks[index - 1].position;
            const end = breaks[index].position;
            const lineNodes = [];
            for (let nodeIndex = start; nodeIndex <= end; nodeIndex += 1) {
                const node = nodes[nodeIndex];
                if (!node) continue;
                if (node.type === 'glue' && (nodeIndex === start || nodeIndex === end)) continue;
                lineNodes.push({ ...node });
            }
            const measure = options.measures[Math.min(index - 1, options.measures.length - 1)] || this.metrics.content.width;
            const offset = options.lineOffsets[Math.min(index - 1, options.lineOffsets.length - 1)] || 0;
            lines.push({
                nodes: lineNodes,
                measure,
                offset,
                ratio: breaks[index].ratio || 0,
                isFinal: index === breaks.length - 1,
                hyphenated: Boolean(lineNodes.at(-1)?.type === 'penalty' && lineNodes.at(-1)?.penalty === 100),
                align: options.align || 'justify'
            });
        }
        return lines;
    }

    countLineWords(line = {}) {
        const nodes = Array.isArray(line.nodes) ? line.nodes : [];
        let count = 0;
        let previousWasGlue = true;
        nodes.forEach((node) => {
            if (!node) return;
            if (node.type === 'glue') {
                previousWasGlue = true;
                return;
            }
            if (node.type === 'penalty') return;
            if (node.type === 'box' && node.value) {
                if (previousWasGlue) count += 1;
                previousWasGlue = false;
            }
        });
        return count;
    }

    getLineGeometry(globalLine) {
        const linesPerPage = Math.max(1, Math.floor(this.metrics.content.height / this.metrics.typographyLineHeightPx || 1));
        const spreadLineCount = linesPerPage * 2;
        const spreadIndex = Math.floor(globalLine / spreadLineCount);
        const spreadLine = globalLine % spreadLineCount;
        const side = spreadLine < linesPerPage ? 'left' : 'right';
        return {
            spreadIndex,
            side,
            pageLine: side === 'left' ? spreadLine : spreadLine - linesPerPage
        };
    }

    getSpread(index = this.currentSpreadIndex) {
        return this.spreads[Math.max(0, Number(index || 0))] || { index: 0, left: [], right: [] };
    }

    getCurrentSpread() {
        return this.getSpread(this.currentSpreadIndex);
    }

    setCurrentSpread(index = 0) {
        this.currentSpreadIndex = Math.max(0, Math.min(Math.round(Number(index || 0)), Math.max(0, this.spreads.length - 1)));
        this.publish();
        return this.currentSpreadIndex;
    }

    publish() {
        document.dispatchEvent(new CustomEvent('book-pagination:spread-updated', {
            detail: {
                spread: this.getCurrentSpread(),
                spreadIndex: this.currentSpreadIndex,
                spreadCount: this.spreads.length,
                latestBlockId: this.latestBlockId,
                latestRenderedBlockId: this.latestRenderedBlockId
            }
        }));
    }
}

const bookPagination = new BookPaginationModule();

export { bookPagination as BookPagination };

if (window.moduleRegistry) {
    window.moduleRegistry.register(bookPagination);
}

window.BookPagination = bookPagination;