import * as fs from "fs";
import * as path from "path";

// ─── Extension Imports ─────────────────────────────────────────────────────

import {
  run as runIntegrityGuard,
} from "./extensions/integrity-guard";

import {
  run as runProgressTracker,
} from "./extensions/progress-tracker";

// ─── Types ─────────────────────────────────────────────────────────────────

export type { PiscesConfig } from "./extensions/lib/config";
export { loadConfig, validateConfig, deepMerge, getConfigSearchPaths } from "./extensions/lib/config";

import type { PiscesConfig } from "./extensions/lib/config";
import { loadConfig, getConfigSearchPaths } from "./extensions/lib/config";

export interface SessionState {
  startTime: Date;
  skillsUsed: string[];
  topicsWorked: string[];
  warningIssuedAt: number | null;
}

export interface SkillCallContext {
  skillName: string;
  userInput: string;
  sessionState: SessionState;
}

export interface StartupResult {
  contextInjection: string;
  config: PiscesConfig;
}

export interface SkillCallResult {
  proceed: boolean;
  injection: string;
}

export interface SessionEndResult {
  nudge: string | null;
  summary: string | null;
}

// ─── Package Metadata ──────────────────────────────────────────────────────

export const PACKAGE_NAME = "pisces";
export const PACKAGE_VERSION = ((): string => {
  try {
    const pkg = JSON.parse(
      fs.readFileSync(path.join(__dirname, "..", "package.json"), "utf-8")
    ) as { version: string };
    return pkg.version;
  } catch {
    return "0.0.0";
  }
})();
export const SKILLS = ["attempt"] as const;

export type SkillName = (typeof SKILLS)[number];

// ─── Session State ─────────────────────────────────────────────────────────

export function createSessionState(): SessionState {
  return {
    startTime: new Date(),
    skillsUsed: [],
    topicsWorked: [],
    warningIssuedAt: null,
  };
}

// ─── Lifecycle Hooks ────────────────────────────────────────────────────────

export function onLoad(): { ok: boolean; message: string } {
  const nodeVersion = process.version;
  const major = parseInt(nodeVersion.slice(1).split(".")[0], 10);

  if (major < 18) {
    return {
      ok: false,
      message: `Pisces requires Node.js >= 18. Current: ${nodeVersion}. Please upgrade.`,
    };
  }

  const config = loadConfig();
  const configSource = getConfigSearchPaths().find((p: string) => {
    try { return fs.existsSync(p); } catch { return false; }
  }) ?? "defaults";

  return {
    ok: true,
    message: `Pisces ${PACKAGE_VERSION} loaded. Config: ${configSource}. Integrity guard: ${
      config.integrity?.enabled !== false ? "on" : "off"
    }.`,
  };
}

export function onStartup(state: SessionState): StartupResult {
  const config = loadConfig();
  const injection = buildConfigInjection(config);

  // state is retained for future extensions that accumulate context
  void state;

  return {
    contextInjection: injection,
    config,
  };
}

export function onDirectoryChange(_state: SessionState): {
  contextInjection: string;
  message: string | null;
} {
  return { contextInjection: "", message: null };
}

export function onSkillCall(context: SkillCallContext): SkillCallResult {
  const { skillName, userInput, sessionState } = context;
  const config = loadConfig();

  if (!sessionState.skillsUsed.includes(skillName)) {
    sessionState.skillsUsed.push(skillName);
  }

  if (config.integrity?.enabled === false) {
    return { proceed: true, injection: "" };
  }

  const guardResult = runIntegrityGuard({ skillName, userInput, strictness: config.integrity?.strictness });

  return {
    proceed: true,
    injection: guardResult.inject,
  };
}

export function onSessionEnd(state: SessionState): SessionEndResult {
  const config = loadConfig();
  const durationMinutes = Math.round(
    (Date.now() - state.startTime.getTime()) / 60_000
  );

  const trackerResult = runProgressTracker({
    sessionDurationMinutes: durationMinutes,
    skillsUsed: state.skillsUsed,
    topicsWorked: state.topicsWorked,
  });

  return {
    nudge: config.productivity?.burnout_nudges !== false ? trackerResult.nudge : null,
    summary: config.productivity?.weekly_summary !== false ? trackerResult.weeklySummary : null,
  };
}

export function onMidSession(state: SessionState): { warning: string | null } {
  const config = loadConfig();
  const warnAt = config.productivity?.session_warning_minutes ?? 180;

  if (!config.productivity?.burnout_nudges) return { warning: null };

  const elapsedMinutes = Math.round(
    (Date.now() - state.startTime.getTime()) / 60_000
  );

  if (elapsedMinutes >= warnAt && state.warningIssuedAt === null) {
    state.warningIssuedAt = elapsedMinutes;
    return {
      warning: `🐠 You've been at this for ${elapsedMinutes} minutes. Time for a short break — your brain will thank you.`,
    };
  }

  return { warning: null };
}

// ─── Context Injection Helpers ─────────────────────────────────────────────

function buildConfigInjection(config: PiscesConfig): string {
  const hints: string[] = [];

  if (config.student?.name) {
    hints.push(`Student name: ${config.student.name}`);
  }

  if (config.student?.year_of_study) {
    const yearLabels: Record<number, string> = {
      1: "Freshman (1st year)",
      2: "Sophomore (2nd year)",
      3: "Junior (3rd year)",
      4: "Senior (4th year)",
      5: "Graduate (1st year)",
      6: "Graduate (2nd year+)",
    };
    hints.push(
      `Year of study: ${yearLabels[config.student.year_of_study] ?? config.student.year_of_study}`
    );
  }

  if (config.explanations?.default_depth) {
    hints.push(`Explanation depth preference: ${config.explanations.default_depth}`);
  }

  if (!hints.length) return "";

  return [
    "<!-- USER CONFIG PREFERENCES -->",
    ...hints.map((h) => `<!-- ${h} -->`),
  ].join("\n");
}

// ─── Public Utility API ────────────────────────────────────────────────────

export function isValidSkill(name: string): name is SkillName {
  return (SKILLS as readonly string[]).includes(name);
}

// ─── Workspace API (re-exported for packages/cli) ──────────────────────────
export { findWorkspace, getWorkspaceState, syncWorkspaceState } from "./workspace-detector";

export function describe(): string {
  return [
    `🐠 Pisces v${PACKAGE_VERSION}`,
    `   Domain-agnostic learning engine for Pi Coding Agent`,
    ``,
    `   Skills:     /${SKILLS.join(", /")}`,
    `   Extensions: workspace-gate, integrity-guard, progress-tracker, input-revamp`,
    `   Config:     ~/.pi/pisces.json`,
    ``,
    `   Run any skill with /<name>, e.g. /attempt`,
  ].join("\n");
}