/**
 * Command completions — build the dropdown items for journal input
 * autocomplete based on the current raw text and completions data.
 *
 * Pure function with no component dependencies.
 */

import type { CompletionItem } from "./command-parser";
import type { JournalCompletions } from "./completions";

export interface CompletionsContext {
  data: JournalCompletions;
  isGm: boolean;
}

export function buildCompletions(
  raw: string,
  ctx: CompletionsContext,
): CompletionItem[] {
  const { data, isGm } = ctx;

  const commands = [
    { label: "/roll", kind: "command" as const, insertText: "/roll " },
    { label: "/spark", kind: "command" as const, insertText: "/spark " },
    { label: "/link", kind: "command" as const, insertText: "/link " },
    { label: "/stat", kind: "command" as const, insertText: "/stat " },
  ];

  // Show commands when user types / or starts typing a command name
  if (raw.startsWith("/") && !raw.includes(" ")) {
    const prefix = raw.toLowerCase();
    let matches = commands.filter((c) =>
      c.label.toLowerCase().startsWith(prefix),
    );
    if (!isGm) {
      matches = matches.filter((c) => c.label === "/stat");
    }
    return matches.length > 0
      ? matches
      : [{ label: "未知命令", kind: "no-results", insertText: "" }];
  }

  // After /roll — show dice suggestions
  if (raw.startsWith("/roll ")) {
    const prefix = raw.slice("/roll ".length).toLowerCase();
    const matches = data.dice
      .filter(
        (d) =>
          d.notation.toLowerCase().includes(prefix) ||
          d.label.toLowerCase().includes(prefix),
      )
      .slice(0, 8);
    if (matches.length === 0) {
      return [{ label: "未找到骰子", kind: "no-results", insertText: "" }];
    }
    return matches.map((d) => ({
      label: d.notation,
      kind: "value" as const,
      insertText: "/roll " + d.notation,
    }));
  }

  // After /spark — show spark table suggestions
  if (raw.startsWith("/spark ")) {
    const prefix = raw.slice("/spark ".length).toLowerCase();
    const matches = data.sparkTables
      .filter(
        (s) =>
          s.slug.toLowerCase().includes(prefix) ||
          s.label.toLowerCase().includes(prefix),
      )
      .slice(0, 8);
    if (matches.length === 0) {
      return [{ label: "未找到种子表", kind: "no-results", insertText: "" }];
    }
    return matches.map((s) => ({
      label: `${s.slug} (${s.notation})`,
      kind: "value" as const,
      insertText: `/spark ${s.slug}`,
    }));
  }

  // After /link — show article and heading suggestions
  if (raw.startsWith("/link ")) {
    const prefix = raw.slice("/link ".length).toLowerCase();
    const matches = data.links
      .filter(
        (l) =>
          l.path.toLowerCase().includes(prefix) ||
          l.label.toLowerCase().includes(prefix),
      )
      .slice(0, 8);
    if (matches.length === 0) {
      return [{ label: "未找到链接", kind: "no-results", insertText: "" }];
    }
    return matches.map((l) => {
      const insert = l.section
        ? `/link ${l.path}#${l.section}`
        : `/link ${l.path}`;
      return { label: l.label, kind: "value" as const, insertText: insert };
    });
  }

  // After /stat — show subcommands or stat keys
  if (raw.startsWith("/stat ")) {
    const rest = raw.slice("/stat ".length).trim();

    if (!rest || rest.length < 3) {
      const subs = ["set", "del", "roll"];
      const matches = subs.filter((s) => s.startsWith(rest.toLowerCase()));
      if (matches.length === 0)
        return [{ label: "set/del/roll", kind: "no-results", insertText: "" }];
      return matches.map((s) => ({
        label: `/stat ${s}`,
        kind: "value" as const,
        insertText: `/stat ${s} `,
      }));
    }

    if (rest.startsWith("set ")) {
      const prefix = rest.slice("set ".length).toLowerCase();
      const matches = data.stats
        .filter((s) => s.key.toLowerCase().includes(prefix))
        .slice(0, 8);
      if (matches.length === 0)
        return [{ label: "未找到属性", kind: "no-results", insertText: "" }];
      return matches.map((s) => ({
        label: `${s.key} (${s.label})`,
        kind: "value" as const,
        insertText: `/stat set ${s.key}=`,
      }));
    }

    if (rest.startsWith("del ") || rest.startsWith("roll ")) {
      const [cmd, ...restParts] = rest.split(" ");
      const prefix = restParts.join(" ").toLowerCase();
      const matches = data.stats
        .filter((s) => s.key.toLowerCase().startsWith(prefix))
        .slice(0, 8);
      if (matches.length === 0)
        return [{ label: "未找到属性", kind: "no-results", insertText: "" }];
      return matches.map((s) => ({
        label: `${s.key} (${s.label})`,
        kind: "value" as const,
        insertText: `/stat ${cmd} ${s.key}`,
      }));
    }
  }

  return [];
}