import { canonicalPage } from '@/lib/skills/surfaces';
import { slugify } from '@/lib/skills/uiConfig';
import {
  AGENT_ACCESS, AGENT_STATUSES, DEFAULT_AGENT_ACCESS, DEFAULT_AGENT_ICON,
  DEFAULT_AGENT_STATUS, DEFAULT_KNOWLEDGE_KIND, DEFAULT_PERMISSION_ROLE, DEFAULT_REASONING,
  KNOWLEDGE_KINDS, PERMISSION_ROLES, SUPPORTED_REASONING, isAgentIcon, reasoningFor,
} from './vocabulary';

/**
 * An agent definition's frontmatter, checked and normalized.
 *
 * The same contract `normalizeSkillOwliver` holds, for the same reasons:
 *
 *   - **Everything is optional.** A definition that declares only an id and a
 *     name normalizes to a working agent with documented defaults. That is what
 *     lets the five zero-skill pages have real agents without inventing skills
 *     to fill them.
 *   - **Nothing unknown survives.** Statuses, reasoning modes, pages, icons,
 *     knowledge kinds and permission roles are checked against the closed
 *     tables in `vocabulary.js`; an unrecognised value is a named error rather
 *     than a dropped key.
 *   - **What validates is kept.** One bad entry costs its author that entry and
 *     a message, never the rest of the file.
 *
 * One rule is deliberately *absent*: an agent with no skills is not refused.
 * A skill with no capabilities genuinely cannot answer, which is why the skill
 * validator refuses one — but an agent with no skills still has its page's own
 * responder, which is how Control Center, Hired History, Talent Pool, Activity
 * and Profile answer today. Refusing them would force placeholder skills into
 * the registry to make the UI look complete, and a registry that lies about
 * what exists is worse than a short list.
 */

/** What a definition that declares nothing gets. */
export const NO_PERMISSIONS = Object.freeze({
  owner: '',
  access: DEFAULT_AGENT_ACCESS,
  people: [],
});

const asList = (value) => {
  if (Array.isArray(value)) return value;
  if (value === null || value === undefined || value === '') return [];
  return [value];
};

const trimmed = (value) => String(value ?? '').trim();

/** Deduped, order preserved — the order an author wrote is the order shown. */
function uniqueStrings(raw, { where, errors, label }) {
  const seen = new Set();
  const out = [];

  asList(raw).forEach((entry, index) => {
    const value = trimmed(entry);
    if (!value) {
      errors.push(`${where}[${index}]: ${label} cannot be blank.`);
      return;
    }
    if (seen.has(value)) return;
    seen.add(value);
    out.push(value);
  });

  return out;
}

/**
 * The pages this agent covers, as canonical surface keys.
 *
 * Through `canonicalPage`, so a definition may write an alias — `university`
 * for `krow-forge` — exactly as a skill may, and the two vocabularies cannot
 * drift apart. An unknown page is an error rather than a silently dropped
 * entry, because a page nobody recognises is an agent that will never appear
 * anywhere and give no reason why.
 */
function normalizePages(raw, { errors }) {
  const seen = new Set();
  const pages = [];

  asList(raw).forEach((entry, index) => {
    const written = trimmed(entry);
    if (!written) {
      errors.push(`pages[${index}]: a page cannot be blank.`);
      return;
    }
    const canonical = canonicalPage(written);
    if (!canonical) {
      errors.push(`pages[${index}]: \`${written}\` is not a page this product has.`);
      return;
    }
    if (seen.has(canonical)) return;
    seen.add(canonical);
    pages.push(canonical);
  });

  return pages;
}

/**
 * One conversation starter, in either the plain-string or the mapping form.
 *
 * The same two shapes `normalizeSuggestion` accepts for skills, so an author
 * who has written one has already written the other.
 */
function normalizeStarter(raw, { errors, index }) {
  const where = `starters[${index}]`;

  if (typeof raw === 'string' || typeof raw === 'number') {
    const label = trimmed(raw);
    if (!label) {
      errors.push(`${where}: a starter needs text.`);
      return null;
    }
    return { label, prompt: label };
  }

  if (!raw || typeof raw !== 'object' || Array.isArray(raw)) {
    errors.push(`${where}: a starter must be a line of text, or a mapping of options.`);
    return null;
  }

  const label = trimmed(raw.label ?? raw.prompt);
  if (!label) {
    errors.push(`${where}: a starter needs a \`label\`.`);
    return null;
  }

  /* A starter with no prompt of its own asks what it says. */
  return { label, prompt: trimmed(raw.prompt) || label };
}

/**
 * One knowledge entry.
 *
 * Modelled as a document with an id and a body even though it is one authored
 * note today, because that is the shape a retrieval layer reads — see
 * `knowledge.js`. Getting the shape right now is what makes a later move to a
 * real store a change of transport rather than a change of format.
 */
function normalizeKnowledge(raw, { errors, index }) {
  const where = `knowledge[${index}]`;

  if (typeof raw === 'string' || typeof raw === 'number') {
    const body = trimmed(raw);
    if (!body) {
      errors.push(`${where}: a knowledge entry needs text.`);
      return null;
    }
    return { id: slugify(body.slice(0, 40)) || `k${index + 1}`, label: body.slice(0, 60), kind: DEFAULT_KNOWLEDGE_KIND, body, url: '' };
  }

  if (!raw || typeof raw !== 'object' || Array.isArray(raw)) {
    errors.push(`${where}: a knowledge entry must be a line of text, or a mapping of options.`);
    return null;
  }

  const label = trimmed(raw.label);
  const body = trimmed(raw.body);
  const url = trimmed(raw.url);

  if (!label && !body) {
    errors.push(`${where}: a knowledge entry needs a \`label\` or a \`body\`.`);
    return null;
  }

  const kind = trimmed(raw.kind) || DEFAULT_KNOWLEDGE_KIND;
  if (!KNOWLEDGE_KINDS.includes(kind)) {
    errors.push(`${where}: \`${kind}\` is not a knowledge kind. Use one of ${KNOWLEDGE_KINDS.join(', ')}.`);
    return null;
  }

  if (kind === 'link' && !url) {
    errors.push(`${where}: a \`link\` needs a \`url\`.`);
    return null;
  }

  return {
    id: trimmed(raw.id) || slugify(label) || `k${index + 1}`,
    label: label || body.slice(0, 60),
    kind,
    body,
    url,
  };
}

/** Who owns the agent, who may reach it, and what they may do. */
function normalizePermissions(raw, { errors }) {
  if (raw === null || raw === undefined) return { ...NO_PERMISSIONS };

  if (typeof raw !== 'object' || Array.isArray(raw)) {
    errors.push('permissions: must be a mapping of `owner`, `access` and `people`.');
    return { ...NO_PERMISSIONS };
  }

  const access = trimmed(raw.access) || DEFAULT_AGENT_ACCESS;
  if (!AGENT_ACCESS.includes(access)) {
    errors.push(`permissions.access: \`${access}\` is not an access mode. Use one of ${AGENT_ACCESS.join(', ')}.`);
  }

  const people = [];
  asList(raw.people).forEach((entry, index) => {
    const where = `permissions.people[${index}]`;
    if (!entry || typeof entry !== 'object' || Array.isArray(entry)) {
      errors.push(`${where}: must be a mapping of \`user\` and \`role\`.`);
      return;
    }
    const user = trimmed(entry.user);
    if (!user) {
      errors.push(`${where}: needs a \`user\`.`);
      return;
    }
    const role = trimmed(entry.role) || DEFAULT_PERMISSION_ROLE;
    if (!PERMISSION_ROLES.includes(role)) {
      errors.push(`${where}: \`${role}\` is not a role. Use one of ${PERMISSION_ROLES.join(', ')}.`);
      return;
    }
    people.push({ user, role });
  });

  return {
    owner: trimmed(raw.owner),
    access: AGENT_ACCESS.includes(access) ? access : DEFAULT_AGENT_ACCESS,
    people,
  };
}

/**
 * One agent's frontmatter → `{ agent, errors }`.
 *
 * `agentId` is the id already derived by the caller, used to reject an agent
 * that names itself as its own subagent — a cycle the runtime would otherwise
 * have to defend against on every turn.
 */
export function normalizeAgent(raw, { agentId = '', body = '' } = {}) {
  const errors = [];
  const data = raw && typeof raw === 'object' && !Array.isArray(raw) ? raw : {};

  if (raw && (typeof raw !== 'object' || Array.isArray(raw))) {
    errors.push('An agent definition must be a mapping of options.');
  }

  const status = trimmed(data.status) || DEFAULT_AGENT_STATUS;
  if (!AGENT_STATUSES.includes(status)) {
    errors.push(`status: \`${status}\` is not a status. Use one of ${AGENT_STATUSES.join(', ')}.`);
  }

  const reasoning = trimmed(data.reasoning) || DEFAULT_REASONING;
  if (!reasoningFor(reasoning)) {
    errors.push(`reasoning: \`${reasoning}\` is not a reasoning mode. Use one of ${SUPPORTED_REASONING.join(', ')}.`);
  }

  const icon = trimmed(data.icon) || DEFAULT_AGENT_ICON;
  if (!isAgentIcon(icon)) {
    errors.push(`icon: \`${icon}\` is not an icon this product has.`);
  }

  /* A version is an integer that only ever goes up. Anything else is an
     authoring slip, and reading it as 1 is kinder than refusing the file —
     but it is still reported, because a definition that thinks it is v3 and
     registers as v1 will publish over something. */
  let version = 1;
  if (data.version !== undefined && data.version !== null && data.version !== '') {
    const parsed = Number(data.version);
    if (!Number.isInteger(parsed) || parsed < 1) {
      errors.push(`version: \`${data.version}\` is not a whole number of 1 or more.`);
    } else {
      version = parsed;
    }
  }

  const subagents = uniqueStrings(data.subagents, {
    where: 'subagents', errors, label: 'a subagent id',
  }).filter((id) => {
    if (agentId && id === agentId) {
      errors.push('subagents: an agent cannot be its own subagent.');
      return false;
    }
    return true;
  });

  const starters = asList(data.starters)
    .map((entry, index) => normalizeStarter(entry, { errors, index }))
    .filter(Boolean);

  const knowledge = asList(data.knowledge)
    .map((entry, index) => normalizeKnowledge(entry, { errors, index }))
    .filter(Boolean);

  return {
    agent: {
      status: AGENT_STATUSES.includes(status) ? status : DEFAULT_AGENT_STATUS,
      version,
      /* When to reach for this agent, in the author's words. Shown in the
         switcher and carried to the runtime; never matched on, so it can be
         prose rather than keywords. */
      trigger: trimmed(data.trigger),
      reasoning: reasoningFor(reasoning) ? reasoning : DEFAULT_REASONING,
      icon: isAgentIcon(icon) ? icon : DEFAULT_AGENT_ICON,
      webSearch: data.webSearch === true || data.web_search === true,
      pages: normalizePages(data.pages, { errors }),
      skills: uniqueStrings(data.skills, { where: 'skills', errors, label: 'a skill id' }),
      subagents,
      knowledge,
      starters,
      permissions: normalizePermissions(data.permissions, { errors }),
      /* The body's own sections, read by the caller and passed through here so
         one record carries everything a definition said. */
      instructions: trimmed(body),
    },
    errors,
  };
}