import type { Theme, ThemeColor } from "@earendil-works/pi-coding-agent";
import {
  Markdown,
  type MarkdownTheme,
  truncateToWidth,
  visibleWidth,
} from "@earendil-works/pi-tui";
import type { ZentuiConfig } from "../../../app/config/shell.ts";
import {
  EDITOR_ACCENT_FALLBACK,
  EDITOR_BORDER_FALLBACK,
  renderThemeStyleOrFallbackStrict,
} from "../../../shared/style.ts";
import { sanitizeUserMessageSourceText } from "./user-message-osc.ts";

export type UserMessageStyleRenderInput = {
  text: string;
  width: number;
  theme?: Theme;
  config: ZentuiConfig;
};

function themeFg(
  theme: Theme | undefined,
  color: ThemeColor,
  text: string,
): string {
  return theme ? theme.fg(color, text) : text;
}

function makeMarkdownTheme(theme: Theme | undefined): MarkdownTheme {
  return {
    heading: (text) => themeFg(theme, "mdHeading", text),
    link: (text) => themeFg(theme, "mdLink", text),
    linkUrl: (text) => themeFg(theme, "mdLinkUrl", text),
    code: (text) => themeFg(theme, "mdCode", text),
    codeBlock: (text) => themeFg(theme, "mdCodeBlock", text),
    codeBlockBorder: (text) => themeFg(theme, "mdCodeBlockBorder", text),
    quote: (text) => themeFg(theme, "mdQuote", text),
    quoteBorder: (text) => themeFg(theme, "mdQuoteBorder", text),
    hr: (text) => themeFg(theme, "mdHr", text),
    listBullet: (text) => themeFg(theme, "mdListBullet", text),
    bold: (text) => (theme ? theme.bold(text) : text),
    italic: (text) => (theme ? theme.italic(text) : text),
    underline: (text) => (theme ? theme.underline(text) : text),
    strikethrough: (text) => (theme ? theme.strikethrough(text) : text),
  };
}

function renderMarkdown(
  text: string,
  width: number,
  theme: Theme | undefined,
): string[] {
  const renderer = new Markdown(text, 0, 0, makeMarkdownTheme(theme), {
    color: (content) => themeFg(theme, "userMessageText", content),
  });
  const lines = renderer.render(Math.max(1, width));
  return lines.length > 0 ? lines : [""];
}

function trimMarkdownPadding(line: string): string {
  return line.replace(/ +((?:\x1b\[[0-?]*[ -/]*[@-~])*)$/, "$1");
}

function fillLine(content: string, width: number): string {
  const truncated = truncateToWidth(content, Math.max(0, width), "");
  return `${truncated}${" ".repeat(Math.max(0, width - visibleWidth(truncated)))}`;
}

function accent(
  theme: Theme | undefined,
  config: ZentuiConfig,
  text: string,
): string {
  return theme
    ? renderThemeStyleOrFallbackStrict(
        theme,
        config.colors.editorAccent,
        EDITOR_ACCENT_FALLBACK,
        text,
      )
    : text;
}

function border(
  theme: Theme | undefined,
  config: ZentuiConfig,
  text: string,
): string {
  return theme
    ? renderThemeStyleOrFallbackStrict(
        theme,
        config.colors.editorBorder,
        EDITOR_BORDER_FALLBACK,
        text,
      )
    : text;
}

function renderRail(theme: Theme | undefined, config: ZentuiConfig): string {
  return `${accent(theme, config, config.icons.rail)} `;
}

function renderFramed({
  text,
  width,
  theme,
  config,
}: UserMessageStyleRenderInput): string[] {
  if (width <= 0) return [""];
  const rail = renderRail(theme, config);
  const contentWidth = Math.max(1, width - visibleWidth(rail));
  const body = renderMarkdown(text, contentWidth, theme);
  const row = (line: string) => {
    const available = Math.max(0, width - visibleWidth(rail));
    return truncateToWidth(`${rail}${fillLine(line, available)}`, width, "");
  };
  const rule = truncateToWidth(
    border(theme, config, "─".repeat(width)),
    width,
    "",
  );
  return [rule, row(""), ...body.map(row), row(""), rule];
}

function renderFramedCopyFriendly({
  text,
  width,
  theme,
  config,
}: UserMessageStyleRenderInput): string[] {
  if (width <= 0) return [""];
  const prefix = width > 1 ? " " : "";
  const body = renderMarkdown(text, width - prefix.length, theme).map((line) =>
    fillLine(`${prefix}${line}`, width),
  );
  const rule = truncateToWidth(
    border(theme, config, "─".repeat(width)),
    width,
    "",
  );
  return [rule, "", ...body, "", rule];
}

function renderCompact({
  text,
  width,
  theme,
  config,
}: UserMessageStyleRenderInput): string[] {
  if (width <= 0) return [""];
  const rail = renderRail(theme, config);
  const railWidth = visibleWidth(rail);
  if (width <= railWidth) {
    return renderMarkdown(text, width, theme).map((line) =>
      truncateToWidth(trimMarkdownPadding(line), width, ""),
    );
  }
  const contentWidth = width - railWidth;
  return renderMarkdown(text, contentWidth, theme).map((line) =>
    truncateToWidth(`${rail}${trimMarkdownPadding(line)}`, width, ""),
  );
}

function renderLabeled({
  text,
  width,
  theme,
  config,
}: UserMessageStyleRenderInput): string[] {
  if (width <= 0) return [""];
  if (width <= 2) {
    return renderMarkdown(text, width, theme).map((line) =>
      truncateToWidth(line, width, ""),
    );
  }

  const horizontalPadding = width >= 5 ? 1 : 0;
  const contentWidth = Math.max(1, width - 2 - horizontalPadding * 2);
  const body = renderMarkdown(text, contentWidth, theme);
  const top =
    width >= 9
      ? `${border(theme, config, "╭─")}${accent(theme, config, " User ")}${border(
          theme,
          config,
          `${"─".repeat(Math.max(0, width - 9))}╮`,
        )}`
      : border(theme, config, `╭${"─".repeat(Math.max(0, width - 2))}╮`);
  const padding = " ".repeat(horizontalPadding);
  const side = (line: string) =>
    `${border(theme, config, "│")}${padding}${fillLine(line, contentWidth)}${padding}${border(
      theme,
      config,
      "│",
    )}`;
  const bottom = border(
    theme,
    config,
    `╰${"─".repeat(Math.max(0, width - 2))}╯`,
  );
  return [top, ...body.map(side), bottom];
}

export function userMessageStyleCacheKey(config: ZentuiConfig): string {
  const messages = config.components.userMessages;
  switch (messages.style) {
    case "framed":
      return [
        "framed",
        config.colors.editorAccent ?? "",
        config.colors.editorBorder ?? "",
        config.icons.rail,
      ].join("\0");
    case "framed-copy-friendly":
      return ["framed-copy-friendly", config.colors.editorBorder ?? ""].join(
        "\0",
      );
    case "compact":
      return [
        "compact",
        config.colors.editorAccent ?? "",
        config.icons.rail,
      ].join("\0");
    case "labeled":
      return [
        "labeled",
        config.colors.editorAccent ?? "",
        config.colors.editorBorder ?? "",
        "User:v1",
      ].join("\0");
  }
}

function renderSelectedUserMessageStyle(
  input: UserMessageStyleRenderInput,
): string[] {
  switch (input.config.components.userMessages.style) {
    case "framed":
      return renderFramed(input);
    case "framed-copy-friendly":
      return renderFramedCopyFriendly(input);
    case "compact":
      return renderCompact(input);
    case "labeled":
      return renderLabeled(input);
  }
}

export function renderUserMessageStyle(
  input: UserMessageStyleRenderInput,
): string[] {
  // Raw user input is a terminal trust boundary. Strip every source control,
  // including OSC 8; Markdown may add its own validated links afterward.
  return renderSelectedUserMessageStyle({
    ...input,
    text: sanitizeUserMessageSourceText(input.text),
  });
}