import { apiGet, apiPost, apiPatch, apiDelete } from "@/api/client";

/** How a rule reaches a session (milestone 307). */
export type RuleTier = "always_on" | "conditional";

/**
 * A typed edge between two rules. Each kind exists because its absence forced
 * a workaround: merging two rules into one row, writing an override as a
 * near-copy, or leaving a local addendum with nothing to say it is one.
 */
export type RuleRelationKind = "co_surfaces" | "overrides" | "elaborates";

export interface RuleRelation {
  id: number;
  kind: RuleRelationKind;
  /** The rule at the OTHER end. */
  rule_id: number;
  direction: "outgoing" | "incoming";
  note: string;
}

export interface Rulebook {
  id: number;
  owner_user_id: number;
  title: string;
  description: string;
  always_on: boolean;
  created_at: string | null;
  updated_at: string | null;
}

export interface RulebookTopic {
  id: number;
  rulebook_id: number;
  title: string;
  description: string;
  order_index: number;
  created_at: string | null;
  updated_at: string | null;
}

export interface Rule {
  id: number;
  topic_id: number | null;
  project_id: number | null;
  title: string;
  statement: string;
  /** WHEN this rule fires — the trigger, not the instruction. */
  when_to_apply: string;
  /**
   * always_on preloads into every session; conditional is reachable and
   * surfaced when its trigger fires. A rule with no tier set behaves as
   * always_on, which is how every rule behaved before this existed.
   */
  tier: RuleTier;
  why: string;
  how_to_apply: string;
  /** The note or task that caused this rule, if one was recorded. */
  arose_from_id: number | null;
  order_index: number;
  created_at: string | null;
  updated_at: string | null;
  /** Present only when the rule has them (the server omits empty keys). */
  systems?: { id: number; name: string }[];
  relations?: RuleRelation[];
}

/**
 * A rule as a LIST ROW — services.rulebooks.rule_brief's output. Carries the
 * age deliberately: a rule written before the capability it duplicates is
 * otherwise indistinguishable, at a glance, from one still doing work.
 */
export interface RuleHeader {
  id: number;
  title: string;
  statement: string;
  topic_id: number | null;
  tier: RuleTier;
  /** A date (YYYY-MM-DD), not a timestamp. */
  updated_at: string | null;
  when_to_apply?: string;
  arose_from_id?: number;
}

export interface ApplicableRules {
  // Both lists are rule_brief's output — the SAME builder, so they are
  // described the same way here rather than as two hand-written shapes that
  // drift from it and from each other (which is what the server side had).
  rules: (RuleHeader & {
    topic_title: string;
    rulebook_id: number;
    rulebook_title: string;
  })[];
  project_rules: RuleHeader[];
  suppressed_rules: {
    id: number;
    title: string;
    topic_id: number;
    topic_title: string;
    rulebook_id: number;
    rulebook_title: string;
  }[];
  suppressed_topics: {
    id: number;
    title: string;
    rulebook_id: number;
    rulebook_title: string;
  }[];
  truncated: boolean;
  subscribed_rulebooks: { id: number; title: string }[];
  /** Always-on rulebooks this project opted out of at inception (milestone 297). */
  excluded_always_on: { id: number; title: string }[];
}

// ── Rulebooks ───────────────────────────────────────────────────────

export async function listRulebooks(): Promise<Rulebook[]> {
  const data = await apiGet<{ rulebooks: Rulebook[] }>("/api/rulebooks");
  return data.rulebooks;
}

export async function getRulebook(id: number): Promise<Rulebook & { topics: RulebookTopic[] }> {
  return apiGet(`/api/rulebooks/${id}`);
}

export async function createRulebook(data: { title: string; description?: string }): Promise<Rulebook> {
  return apiPost("/api/rulebooks", data);
}

export async function updateRulebook(id: number, data: Partial<{ title: string; description: string; always_on: boolean }>): Promise<Rulebook> {
  return apiPatch(`/api/rulebooks/${id}`, data);
}

export async function deleteRulebook(id: number): Promise<void> {
  return apiDelete(`/api/rulebooks/${id}`);
}

// ── Topics ─────────────────────────────────────────────────────────

export async function listTopics(rulebookId: number): Promise<RulebookTopic[]> {
  const data = await apiGet<{ topics: RulebookTopic[] }>(`/api/rulebooks/${rulebookId}/topics`);
  return data.topics;
}

export async function createTopic(rulebookId: number, data: { title: string; description?: string; order_index?: number }): Promise<RulebookTopic> {
  return apiPost(`/api/rulebooks/${rulebookId}/topics`, data);
}

export async function updateTopic(id: number, data: Partial<{ title: string; description: string; order_index: number }>): Promise<RulebookTopic> {
  return apiPatch(`/api/rulebook-topics/${id}`, data);
}

export async function deleteTopic(id: number): Promise<void> {
  return apiDelete(`/api/rulebook-topics/${id}`);
}

// ── Rules ──────────────────────────────────────────────────────────

export async function listRules(filters: { rulebook_id?: number; topic_id?: number; project_id?: number } = {}): Promise<Rule[]> {
  const params = new URLSearchParams();
  if (filters.rulebook_id) params.set("rulebook_id", String(filters.rulebook_id));
  if (filters.topic_id) params.set("topic_id", String(filters.topic_id));
  if (filters.project_id) params.set("project_id", String(filters.project_id));
  const qs = params.toString();
  const data = await apiGet<{ rules: Rule[] }>(`/api/rules${qs ? `?${qs}` : ""}`);
  return data.rules;
}

export async function getRule(id: number): Promise<Rule> {
  return apiGet(`/api/rules/${id}`);
}

/** The fields both write paths accept. `system_ids` REPLACES a rule's areas. */
export interface RuleWrite {
  title: string;
  statement: string;
  when_to_apply: string;
  tier: RuleTier;
  why: string;
  how_to_apply: string;
  order_index: number;
  system_ids: number[];
  arose_from_id: number | null;
}

export async function createRule(topicId: number, data: Partial<RuleWrite> & { title: string; statement: string }): Promise<Rule> {
  return apiPost(`/api/rulebook-topics/${topicId}/rules`, data);
}

export async function updateRule(id: number, data: Partial<RuleWrite>): Promise<Rule> {
  return apiPatch(`/api/rules/${id}`, data);
}

/** Draw a typed edge from one rule to another. Idempotent. */
export async function relateRules(
  fromRuleId: number,
  data: { to_rule_id: number; kind: RuleRelationKind; note?: string },
): Promise<{ id: number }> {
  return apiPost(`/api/rules/${fromRuleId}/relations`, data);
}

export async function unrelateRules(relationId: number): Promise<void> {
  return apiDelete(`/api/rule-relations/${relationId}`);
}

export async function deleteRule(id: number): Promise<void> {
  return apiDelete(`/api/rules/${id}`);
}

// ── Subscriptions ──────────────────────────────────────────────────

export async function subscribeProject(projectId: number, rulebookId: number): Promise<void> {
  await apiPost(`/api/projects/${projectId}/rulebook-subscriptions`, { rulebook_id: rulebookId });
}

export async function unsubscribeProject(projectId: number, rulebookId: number): Promise<void> {
  return apiDelete(`/api/projects/${projectId}/rulebook-subscriptions/${rulebookId}`);
}

export async function getProjectApplicableRules(projectId: number): Promise<ApplicableRules> {
  return apiGet(`/api/projects/${projectId}/rules`);
}

export async function createProjectRule(
  projectId: number,
  data: Partial<RuleWrite> & { statement: string },
): Promise<Rule> {
  return apiPost(`/api/projects/${projectId}/rules`, data);
}

// ── Suppressions ───────────────────────────────────────────────────

export async function suppressRuleForProject(projectId: number, ruleId: number): Promise<void> {
  await apiPost(`/api/projects/${projectId}/suppressions/rules/${ruleId}`, {});
}

export async function unsuppressRuleForProject(projectId: number, ruleId: number): Promise<void> {
  return apiDelete(`/api/projects/${projectId}/suppressions/rules/${ruleId}`);
}

export async function suppressTopicForProject(projectId: number, topicId: number): Promise<void> {
  await apiPost(`/api/projects/${projectId}/suppressions/topics/${topicId}`, {});
}

export async function unsuppressTopicForProject(projectId: number, topicId: number): Promise<void> {
  return apiDelete(`/api/projects/${projectId}/suppressions/topics/${topicId}`);
}

// ── Always-on exclusions (milestone 297) ────────────────────────────────────

export async function excludeAlwaysOnRulebook(projectId: number, rulebookId: number): Promise<void> {
  await apiPost(`/api/projects/${projectId}/exclusions/rulebooks/${rulebookId}`, {});
}

export async function includeAlwaysOnRulebook(projectId: number, rulebookId: number): Promise<void> {
  await apiDelete(`/api/projects/${projectId}/exclusions/rulebooks/${rulebookId}`);
}