import { readFileSync } from "node:fs";
import { resolve } from "node:path";
import { z } from "zod";
import {
  consultationDomainDefinition,
  consultationDomainIds,
  type ConsultationDomain,
} from "./consultation-domain-registry.ts";
import { resolveLiveJyotishSkill } from "./skill-package-registry.ts";

/**
 * The strict checklist each consultation domain must be read against, named in
 * the vocabulary of the skill's own router rather than this codebase's.
 *
 * Activating the skill hands the model its instructions plus a flat list of
 * every file in the package: on the Jyotish package that is over 1500 paths and
 * about 99KB of undifferentiated filenames, against 30KB of actual method. The
 * one line telling it to open `references/strict-workflow-router.md` is inside
 * that method, so in practice no reference was ever opened and every answer was
 * composed from the model's own background knowledge over server evidence.
 *
 * The route is already decided server-side, and the skill already states which
 * checklist each route requires, so the selection needs no model turn: read the
 * mandated sections here and deliver them with the evidence. A checklist the
 * router does not declare is reported as absent instead of substituted.
 */
const domainMethodology: Readonly<Record<ConsultationDomain, { strictRoute: string | null; eventJudgment: string | null }>> = {
  career: { strictRoute: "career-timing-strict", eventJudgment: "event_judgment_career.md" },
  marriage: { strictRoute: "relationship-timing-strict", eventJudgment: "event_judgment_marriage.md" },
  wealth: { strictRoute: "wealth-timing-strict", eventJudgment: "event_judgment_wealth.md" },
  timing: { strictRoute: "event-timing-strict", eventJudgment: null },
  health: { strictRoute: "health-timing-strict", eventJudgment: null },
  annual: { strictRoute: null, eventJudgment: null },
  general: { strictRoute: null, eventJudgment: null },
  education: { strictRoute: null, eventJudgment: null },
  migration: { strictRoute: null, eventJudgment: null },
  family: { strictRoute: null, eventJudgment: null },
};

const ROUTER_FILE = "references/strict-workflow-router.md";
const SHARED_BASELINE_HEADING = "Shared mandatory baseline";
const SKELETON_FILE = "references/event_judgment_skeleton.md";

/** Per-section and whole-block ceilings, so one long section cannot crowd out the evidence. */
export const METHODOLOGY_SECTION_MAX_CHARS = 6_000;
export const METHODOLOGY_TOTAL_MAX_CHARS = 24_000;
/** How many of the references SKILL.md names are offered as a navigable index. */
export const METHODOLOGY_INDEX_MAX_ENTRIES = 24;

export const consultationMethodologySectionSchema = z.object({
  title: z.string().max(200),
  source: z.string().max(300),
  text: z.string().max(METHODOLOGY_SECTION_MAX_CHARS),
}).strict();

export const consultationMethodologySchema = z.object({
  skill: z.string().max(120),
  version: z.string().max(60),
  /** Domains whose strict checklist the router does not declare; nothing was substituted for them. */
  domains_without_strict_checklist: z.array(z.enum(consultationDomainIds)).max(6),
  sections: z.array(consultationMethodologySectionSchema).max(12),
  /** The references SKILL.md itself names, for reading on purpose with skill_read. */
  further_reading: z.array(z.string().max(300)).max(METHODOLOGY_INDEX_MAX_ENTRIES),
  truncated: z.boolean(),
}).strict();

export type ConsultationMethodology = z.infer<typeof consultationMethodologySchema>;

const skill = resolveLiveJyotishSkill();

/** Live skill files are reread only after process restart; consult requests share one cache. */
const fileCache = new Map<string, string | null>();

function packageFile(relativePath: string): string | null {
  const hit = fileCache.get(relativePath);
  if (hit !== undefined) return hit;
  let content: string | null = null;
  try {
    content = readFileSync(resolve(skill.resolvedPath, relativePath), "utf8");
  } catch {
    content = null;
  }
  fileCache.set(relativePath, content);
  return content;
}

/**
 * The body of one `## ...` section, found by a heading substring so the section
 * numbering in the router can be renumbered without breaking the lookup.
 */
export function markdownSection(source: string, headingContains: string): string | null {
  const lines = source.split("\n");
  const start = lines.findIndex((line) => line.startsWith("## ") && line.includes(headingContains));
  if (start === -1) return null;
  const rest = lines.slice(start + 1);
  const end = rest.findIndex((line) => line.startsWith("## "));
  const body = (end === -1 ? rest : rest.slice(0, end)).join("\n").trim();
  return body.length > 0 ? `${lines[start]}\n\n${body}` : null;
}

function clamp(text: string) {
  return text.length > METHODOLOGY_SECTION_MAX_CHARS
    ? `${text.slice(0, METHODOLOGY_SECTION_MAX_CHARS - 3)}...`
    : text;
}

/**
 * The reference paths SKILL.md names, in the order it names them.
 *
 * Derived rather than listed so that the index follows the skill: when SKILL.md
 * starts pointing somewhere else, the model is offered the new pointer without
 * this file being edited. Paths that are not in the package are dropped, so a
 * stale pointer cannot be advertised as readable.
 */
function namedReferences(instructions: string): string[] {
  const found = new Set<string>();
  for (const match of instructions.matchAll(/references\/[\w./-]*[\w/-]/g)) {
    const path = match[0].replace(/[.]+$/, "");
    if (path.includes("..") || !/\.\w+$/.test(path)) continue;
    if (packageFile(path) === null) continue;
    found.add(path);
    if (found.size >= METHODOLOGY_INDEX_MAX_ENTRIES) break;
  }
  return [...found];
}

const planCache = new Map<string, ConsultationMethodology>();

/**
 * The strict method for one domain plan, read from the live skill tree.
 */
export function consultationMethodologyForDomains(
  domains: readonly ConsultationDomain[],
): ConsultationMethodology | null {
  const unique = [...new Set(domains)];
  const key = unique.join(",");
  const hit = planCache.get(key);
  if (hit) return hit;

  const router = packageFile(ROUTER_FILE);
  const instructions = packageFile("SKILL.md");
  if (!router || !instructions) return null;

  const sections: z.infer<typeof consultationMethodologySectionSchema>[] = [];
  let budget = METHODOLOGY_TOTAL_MAX_CHARS;
  let truncated = false;

  const push = (title: string, source: string, text: string | null) => {
    if (!text) return;
    const bounded = clamp(text);
    if (bounded.length > budget) {
      truncated = true;
      return;
    }
    budget -= bounded.length;
    sections.push({ title, source, text: bounded });
  };

  push("Shared mandatory baseline", ROUTER_FILE, markdownSection(router, SHARED_BASELINE_HEADING));
  push("Full-spectrum invocation", ROUTER_FILE, markdownSection(router, "Full-Spectrum Invocation Contract"));
  push("Event judgment skeleton", SKELETON_FILE, packageFile(SKELETON_FILE));

  const withoutChecklist: ConsultationDomain[] = [];
  for (const domain of unique) {
    const { strictRoute, eventJudgment } = domainMethodology[domain];
    if (!strictRoute) {
      withoutChecklist.push(domain);
    } else {
      const section = markdownSection(router, strictRoute);
      if (section) {
        push(`${consultationDomainDefinition(domain).label} · ${strictRoute}`, ROUTER_FILE, section);
      } else {
        withoutChecklist.push(domain);
      }
    }
    if (eventJudgment) {
      push(`${consultationDomainDefinition(domain).label} · event judgment`, `references/${eventJudgment}`, packageFile(`references/${eventJudgment}`));
    }
  }

  const methodology = consultationMethodologySchema.parse({
    skill: skill.name,
    version: skill.version,
    domains_without_strict_checklist: withoutChecklist,
    sections,
    further_reading: namedReferences(instructions),
    truncated,
  });
  planCache.set(key, methodology);
  return methodology;
}