import { BaseDrawService } from '../../../core/draw/baseDraw';
import type {
    LetterTracingData,
    TracingRow,
} from '../generators/letter-tracing-generator';
import { drawFourLineGrid } from './drawTools';

const LETTER_FACE =
    'Helvetica, Arial, "Segoe UI", Roboto, sans-serif';

type ColumnCompareData = Extract<
    LetterTracingData,
    { mode: 'column-compare' }
>;

export default class ColumnCompareDraw extends BaseDrawService {
    async draw(data: ColumnCompareData) {
        this.prepareDraw();
        await this.drawHeaderAndDivider();
        this.drawContent(data.leftRows, data.rightRows);
        this.drawPrintFooter();
    }

    private drawContent(leftRows: TracingRow[], rightRows: TracingRow[]) {
        const M = 24;
        const y0 = this.currentY + 6;
        const bottom = this.canvasHeight - M;
        const maxR = Math.max(leftRows.length, rightRows.length);
        const rowH = Math.max(36, (bottom - y0) / maxR - 6);
        const gapCol = 16;
        const colW = (this.canvasWidth - M * 2 - gapCol) / 2;

        for (let i = 0; i < leftRows.length; i++) {
            const y = y0 + i * (rowH + 6);
            this.drawTracingRow(leftRows[i], M, y, rowH, colW);
        }
        const xR = M + colW + gapCol;
        for (let i = 0; i < rightRows.length; i++) {
            const y = y0 + i * (rowH + 6);
            this.drawTracingRow(rightRows[i], xR, y, rowH, colW);
        }
    }

    private drawTracingRow(
        row: TracingRow,
        startX: number,
        y: number,
        rowH: number,
        totalWidth: number,
    ) {
        const gap = 4;
        const n = row.cells.length;
        const cellW = n > 0 ? (totalWidth - gap * (n - 1)) / n : totalWidth;
        for (let i = 0; i < n; i++) {
            const cx = startX + i * (cellW + gap);
            drawFourLineGrid(this.ctx, cx, y, cellW, rowH);
            const cell = row.cells[i];
            this.drawCharInCell(
                cell.char,
                cx,
                y,
                cellW,
                rowH,
                cell.opacity,
                cell.isGuide,
                cell.pairChar,
            );
        }
    }

    private drawCharInCell(
        ch: string,
        x: number,
        y: number,
        w: number,
        h: number,
        opacity: number,
        bold: boolean,
        pairChar?: string,
    ) {
        const ctx = this.ctx;
        if (opacity <= 0) return;
        ctx.save();
        ctx.globalAlpha = opacity;
        ctx.fillStyle = bold ? '#1a1a1a' : '#4a4a4a';
        ctx.textAlign = 'center';
        ctx.textBaseline = 'alphabetic';
        const baselineY = y + h * 0.72;

        if (pairChar) {
            const fs = Math.min(h * 0.5, w * 0.22);
            ctx.font = `${bold ? 'bold ' : ''}${fs}px ${LETTER_FACE}`;
            const gap = fs * 0.2;
            const totalW = fs * 2 + gap;
            const x0 = x + w / 2 - totalW / 2;
            ctx.fillText(ch, x0 + fs * 0.5, baselineY);
            ctx.fillText(pairChar, x0 + fs * 1.5 + gap, baselineY);
        } else {
            const fontSize = Math.min(h * 0.72, w * 0.85);
            ctx.font = `${bold ? 'bold ' : ''}${fontSize}px ${LETTER_FACE}`;
            ctx.fillText(ch, x + w / 2, baselineY);
        }
        ctx.restore();
    }
}