import type { CommandMode, WorkPackage } from "./work-package-types";

export type ComposerPackageSuggestion = {
  kind: "package";
  id: string;
  title: string;
  shortName: string;
};

export type ComposerCommandSuggestion = {
  kind: "command";
  mode: CommandMode;
  label: string;
  description: string;
};

export type ComposerSuggestion =
  | ComposerPackageSuggestion
  | ComposerCommandSuggestion;

const AT_TRIGGER = /(^|\s)@([A-Za-z\s-]*)$/;
const SLASH_TRIGGER = /(^|\s)\/([A-Za-z-]*)$/i;

const COMMAND_SUGGESTIONS: ComposerCommandSuggestion[] = [
  {
    kind: "command",
    mode: "ask",
    label: "/ask",
    description: "Ask about the current package context",
  },
  {
    kind: "command",
    mode: "plan",
    label: "/plan",
    description: "Break a package into actionable work",
  },
  {
    kind: "command",
    mode: "change",
    label: "/change",
    description: "Request updates to the current package",
  },
  {
    kind: "command",
    mode: "execute",
    label: "/execute",
    description: "Run the current package flow",
  },
];

function normalize(value: string) {
  return value.trim().replace(/\s+/g, " ").toLowerCase();
}

function packageScore(workPackage: WorkPackage, query: string) {
  const title = normalize(workPackage.title);
  const shortName = normalize(workPackage.shortName);

  if (!query) {
    return 1;
  }

  return (
    Number(shortName.startsWith(query)) * 4 +
    Number(title.startsWith(query)) * 3 +
    Number(shortName.includes(query)) * 2 +
    Number(title.includes(query))
  );
}

export function getComposerSuggestions(
  draft: string,
  workPackages: WorkPackage[],
): ComposerSuggestion[] {
  const atMatch = draft.match(AT_TRIGGER);
  if (atMatch) {
    const query = normalize(atMatch[2] ?? "");

    return workPackages
      .map((workPackage) => ({
        kind: "package" as const,
        id: workPackage.id,
        title: workPackage.title,
        shortName: workPackage.shortName,
        score: packageScore(workPackage, query),
      }))
      .filter((suggestion) => suggestion.score > 0)
      .sort((left, right) => right.score - left.score)
      .slice(0, 6)
      .map((suggestion) => ({
        kind: suggestion.kind,
        id: suggestion.id,
        title: suggestion.title,
        shortName: suggestion.shortName,
      }));
  }

  const slashMatch = draft.match(SLASH_TRIGGER);
  if (slashMatch) {
    const query = normalize(slashMatch[2] ?? "");

    return COMMAND_SUGGESTIONS.filter((suggestion) => {
      return !query || suggestion.mode.startsWith(query);
    });
  }

  return [];
}

export function applyComposerSuggestion(args: {
  draft: string;
  suggestion: ComposerSuggestion;
  selectedWorkPackage?: Pick<WorkPackage, "shortName" | "title">;
}) {
  const { draft, suggestion, selectedWorkPackage } = args;

  if (suggestion.kind === "package") {
    return draft.replace(
      AT_TRIGGER,
      (_, prefix: string) => `${prefix}@${suggestion.shortName} `,
    );
  }

  const packageRef =
    selectedWorkPackage?.shortName || selectedWorkPackage?.title || "";
  const replacement = packageRef
    ? `@${packageRef} ${suggestion.mode} `
    : `/${suggestion.mode} `;

  return draft.replace(SLASH_TRIGGER, (_, prefix: string) => `${prefix}${replacement}`);
}