import type { ExtensionContext } from "@earendil-works/pi-coding-agent";
import { OfficeError } from "../core/errors.ts";
import { STYLE_PRESET_CHOICES, type WordStyleInput } from "./styles.ts";

export type StyleDialogContext = Pick<ExtensionContext, "ui" | "signal">;

function cancelled(): never {
  throw new OfficeError("排版选择已取消。", "STYLE_SELECTION_CANCELLED");
}

async function optionalText(ctx: StyleDialogContext, title: string, placeholder: string): Promise<string | undefined> {
  const value = await ctx.ui.input(title, placeholder, ctx.signal ? { signal: ctx.signal } : undefined);
  if (value === undefined) cancelled();
  const trimmed = value.trim();
  return trimmed || undefined;
}

async function optionalNumber(ctx: StyleDialogContext, title: string, placeholder: string): Promise<number | undefined> {
  const value = await optionalText(ctx, title, placeholder);
  if (value === undefined) return undefined;
  const number = Number(value);
  if (!Number.isFinite(number)) throw new OfficeError(`${title}必须是数字。`, "INVALID_STYLE");
  return number;
}

async function requiredNumber(ctx: StyleDialogContext, title: string, placeholder: string): Promise<number> {
  const value = await optionalNumber(ctx, title, placeholder);
  if (value === undefined) throw new OfficeError(`${title}不能为空。`, "INVALID_STYLE");
  return value;
}

export async function collectCustomStyle(ctx: StyleDialogContext): Promise<WordStyleInput> {
  const chineseBodyFont = await optionalText(ctx, "中文正文字体", "留空使用 SimSun（宋体）");
  const latinBodyFont = await optionalText(ctx, "英文正文字体", "留空使用 Calibri");
  const headingFont = await optionalText(ctx, "标题字体", "留空使用 Microsoft YaHei（微软雅黑）");
  const bodySize = await optionalNumber(ctx, "正文字号（pt）", "留空使用 12.5");
  const titleSize = await optionalNumber(ctx, "主标题字号（pt）", "留空使用 32");
  const heading1Size = await optionalNumber(ctx, "一级标题字号（pt）", "留空使用预设值");
  const heading2Size = await optionalNumber(ctx, "二级标题字号（pt）", "留空使用预设值");
  const heading3Size = await optionalNumber(ctx, "三级标题字号（pt）", "留空使用预设值");
  const lineSpacing = await optionalNumber(ctx, "行距倍数", "留空使用 1.5");
  const firstLineIndent = await optionalNumber(ctx, "首行缩进（cm）", "留空使用预设值；例如 0.74 或 2");
  const accentColor = await optionalText(ctx, "强调色（可选）", "六位十六进制，例如 1F4E79；留空使用预设");
  const marginChoice = await ctx.ui.select("页边距", ["沿用默认", "窄（1.5 cm）", "普通（2.54 cm）", "自定义四边距"], ctx.signal ? { signal: ctx.signal } : undefined);
  if (marginChoice === undefined) cancelled();
  let margins: WordStyleInput["margins"];
  if (marginChoice === "窄（1.5 cm）") margins = { top: 1.5, bottom: 1.5, left: 1.5, right: 1.5 };
  if (marginChoice === "普通（2.54 cm）") margins = { top: 2.54, bottom: 2.54, left: 2.54, right: 2.54 };
  if (marginChoice === "自定义四边距") {
    margins = {
      top: await requiredNumber(ctx, "上页边距（cm）", "例如 2.54"),
      bottom: await requiredNumber(ctx, "下页边距（cm）", "例如 2.54"),
      left: await requiredNumber(ctx, "左页边距（cm）", "例如 2.54"),
      right: await requiredNumber(ctx, "右页边距（cm）", "例如 2.54"),
    };
  }
  const headerFooter = await ctx.ui.confirm("页眉和页码", "是否添加标题页眉与页码？", ctx.signal ? { signal: ctx.signal } : undefined);
  return {
    ...(chineseBodyFont !== undefined ? { chineseBodyFont } : {}),
    ...(latinBodyFont !== undefined ? { latinBodyFont } : {}),
    ...(headingFont !== undefined ? { headingFont } : {}),
    ...(bodySize !== undefined ? { bodySize } : {}),
    ...(titleSize !== undefined ? { titleSize } : {}),
    ...(heading1Size !== undefined ? { heading1Size } : {}),
    ...(heading2Size !== undefined ? { heading2Size } : {}),
    ...(heading3Size !== undefined ? { heading3Size } : {}),
    ...(lineSpacing !== undefined ? { lineSpacing } : {}),
    ...(firstLineIndent !== undefined ? { firstLineIndent } : {}),
    ...(accentColor !== undefined ? { accentColor } : {}),
    ...(margins !== undefined ? { margins } : {}),
    headerFooter,
  };
}

export async function chooseStyle(ctx: StyleDialogContext): Promise<{ stylePreset: "editorial" | "business" | "formal" } | { style: WordStyleInput }> {
  const presetOptions = [...STYLE_PRESET_CHOICES.map((item) => `${item.label} — ${item.summary}`), "自定义 — 设置字体、字号、行距和页边距"];
  const choice = await ctx.ui.select("选择排版", presetOptions, ctx.signal ? { signal: ctx.signal } : undefined);
  if (choice === undefined) cancelled();
  const selectedPreset = STYLE_PRESET_CHOICES.find((item) => choice.startsWith(item.label));
  if (selectedPreset) return { stylePreset: selectedPreset.preset };
  return { style: await collectCustomStyle(ctx) };
}