import { BaseDrawService } from '../../../core/draw/baseDraw';
import type { LetterTracingData } from '../generators/letter-tracing-generator';
import {
    PRINT_CLEARLY_BOLD,
    PRINT_CLEARLY_DASHED,
    fontFamilyOf,
} from '../../shared/data/fontProfiles';
import {
    calcLetterFontSizes,
    drawFourLineGrid,
    drawLetterInFourLineGrid,
    FOUR_LINE_GRID_H,
    loadLetterFont,
    type LetterFontSizes,
} from '../../shared/draw/drawTools';

type UpperLowerData = Extract<
    LetterTracingData,
    { mode: 'letter-tracing-upper-lower' }
>;

/** 页面左右边距（margin，px），用于排版时留白 */
const M = 24;
/** 上下两大区（Uppercase / lowercase）之间的间距 */
const SECTION_GAP = 25;
/** 标题字号 */
const TITLE_SIZE = 28;
/** 标题与第一行四线三格的间距 */
const TITLE_GAP = 25;
/** 同一区域内相邻四线三格行之间的间距 */
const ROW_GAP = 24;
const TITLE_COLOR = '#000';

/** 浅红色描红（不透明 hex，避免打印时半透明发灰） */
const TRACE_LIGHT_RED = '#FF8E8E';

const DASHED_PROFILE = PRINT_CLEARLY_DASHED;
const TITLE_PROFILE = PRINT_CLEARLY_BOLD;
const LETTER_FACE = fontFamilyOf(DASHED_PROFILE);
const TITLE_FACE = fontFamilyOf(TITLE_PROFILE);

/**
 * 字母总览：上区大写、下区小写；每区标题 + 4 行四线三格（7+7+6+6）。
 * 列宽按 7 列均分；后两行 6 字左对齐，与前两行逐列对齐（占前 6 列）。
 */
export default class UpperLowerDraw extends BaseDrawService {
    private letterSizes: LetterFontSizes = calcLetterFontSizes(
        FOUR_LINE_GRID_H,
        DASHED_PROFILE,
    );

    async draw(data: UpperLowerData) {
        this.prepareDraw();
        await Promise.allSettled([
            loadLetterFont(DASHED_PROFILE),
            loadLetterFont(TITLE_PROFILE),
        ]);
        await this.drawHeaderAndDivider();
        this.drawUpperLowerBody(data.upperRows, data.lowerRows);
        await this.drawPrintFooter();
    }

    private drawUpperLowerBody(
        upperRows: string[][],
        lowerRows: string[][],
    ): void {
        const lineW = this.canvasWidth - M * 2;
        const slotW = lineW / 7;

        let y = this.currentY + SECTION_GAP - 7;

        y = this.drawLetterBlock(
            'Uppercase Letters',
            upperRows,
            y,
            lineW,
            slotW,
        );
        y += SECTION_GAP + 7;
        this.drawLetterBlock('lowercase letters', lowerRows, y, lineW, slotW);
    }

    /**
     * 绘制一个分区：居中标题 + 4 行四线三格与字母。
     * @returns 该分区最后一行四线三格底边 Y
     */
    private drawLetterBlock(
        title: string,
        rows: string[][],
        startY: number,
        lineW: number,
        slotW: number,
    ): number {
        const ctx = this.ctx;
        const centerX = M + lineW / 2;

        ctx.save();
        ctx.font = `bold ${TITLE_SIZE}px ${TITLE_FACE}`;
        ctx.fillStyle = TITLE_COLOR;
        ctx.textAlign = 'center';
        ctx.textBaseline = 'top';
        ctx.fillText(title, centerX, startY);
        ctx.restore();

        let y = startY + TITLE_SIZE + TITLE_GAP;

        for (let r = 0; r < rows.length; r++) {
            const chars = rows[r];
            drawFourLineGrid(ctx, M, y, lineW, FOUR_LINE_GRID_H);

            /** 与 7 字行共用列宽 slotW，后两行 6 字左对齐（占前 6 列），与上行逐列对齐 */
            const offsetX = M;
            for (let i = 0; i < chars.length; i++) {
                const cx = offsetX + slotW * (i + 0.5);
                drawLetterInFourLineGrid(
                    ctx,
                    chars[i],
                    cx,
                    y,
                    FOUR_LINE_GRID_H,
                    this.letterSizes,
                    {
                        fontFamily: LETTER_FACE,
                        color: TRACE_LIGHT_RED,
                    },
                );
            }
            y += FOUR_LINE_GRID_H;
            if (r < rows.length - 1) {
                y += ROW_GAP;
            }
        }

        return y;
    }
}