import { describe, expect, it } from "vitest";
import {
  canonicalJson,
  compilePolicy,
  parsePolicyRule,
  policyHash,
  resolvePrecedence,
  type QuorumStateInput,
  type RuleCandidate,
} from "./policy.js";

/**
 * P0 acceptance (design §7): "policy compile is pure + snapshot hash
 * deterministic". Pure-function tests — no DB, no clock.
 */

const quorum: QuorumStateInput = { adminCount: 3, observedParticipants: 12, eligibleParticipants: 8 };

const immediate = { version: 1, mode: "immediate" as const };
const adminOnly = { version: 1, mode: "admin_only" as const, timebox: { duration: "PT1H", onExpire: "reject" as const } };
const quorumRule = {
  version: 1,
  mode: "quorum" as const,
  arms: [
    { kind: "admins" as const, x: 2 },
    { kind: "participants" as const, x: 3, of: "observed" as const },
  ],
  join: "all" as const,
  allowVeto: true,
  timebox: { duration: "PT2H", onExpire: "reject" as const },
};

describe("canonicalJson", () => {
  it("sorts keys and drops undefined, so key order never changes the hash input", () => {
    expect(canonicalJson({ b: 1, a: 2 })).toBe(canonicalJson({ a: 2, b: 1 }));
    expect(canonicalJson({ a: undefined, b: 1 })).toBe(canonicalJson({ b: 1 }));
    expect(canonicalJson({ a: [1, { y: 2, x: 1 }] })).toBe('{"a":[1,{"x":1,"y":2}]}');
  });
  it("keeps array order (order is data)", () => {
    expect(canonicalJson({ a: [2, 1] })).not.toBe(canonicalJson({ a: [1, 2] }));
  });
});

describe("policyHash determinism", () => {
  it("same rule (any key order / explicit defaults) => same hash", () => {
    const a = parsePolicyRule({ mode: "quorum", arms: [{ kind: "admins", x: 2 }], timebox: { duration: "PT2H", onExpire: "reject" } });
    const b = parsePolicyRule({
      timebox: { onExpire: "reject", duration: "PT2H" },
      arms: [{ x: 2, kind: "admins" }],
      mode: "quorum",
      join: "all",
      allowVeto: false,
      anonymity: "named",
      allowSelfApproval: false,
      resetOnChange: true,
      dryRun: false,
      minDwellSeconds: 0,
    });
    expect(policyHash(a)).toBe(policyHash(b));
  });
  it("different policy => different hash", () => {
    expect(policyHash(parsePolicyRule({ mode: "immediate" })))
      .not.toBe(policyHash(parsePolicyRule({ mode: "admin_only", timebox: { duration: "PT1H", onExpire: "reject" } })));
    const withVeto = parsePolicyRule({ mode: "quorum", arms: [{ kind: "admins", x: 2 }], allowVeto: true, timebox: { duration: "PT1H", onExpire: "reject" } });
    const noVeto = parsePolicyRule({ mode: "quorum", arms: [{ kind: "admins", x: 2 }], allowVeto: false, timebox: { duration: "PT1H", onExpire: "reject" } });
    expect(policyHash(withVeto)).not.toBe(policyHash(noVeto));
  });
  it("quorum denominators never enter the hash", () => {
    const rule = parsePolicyRule(quorumRule);
    const withSmall: QuorumStateInput = { adminCount: 1, observedParticipants: 1, eligibleParticipants: 1 };
    const withBig: QuorumStateInput = { adminCount: 99, observedParticipants: 9999, eligibleParticipants: 500 };
    expect(policyHash(rule)).toBe(compilePolicy([{ scope: "workspace", rule }], withSmall).policy_version);
    expect(compilePolicy([{ scope: "workspace", rule }], withSmall).policy_version)
      .toBe(compilePolicy([{ scope: "workspace", rule }], withBig).policy_version);
  });
});

describe("compilePolicy", () => {
  it("candidate order does not change the compiled snapshot", () => {
    const candidates: RuleCandidate[] = [
      { scope: "workspace", rule: parsePolicyRule(immediate) },
      { scope: "account", rule: parsePolicyRule(adminOnly) },
      { scope: "topic", rule: parsePolicyRule(quorumRule) },
    ];
    const forward = compilePolicy(candidates, quorum);
    const shuffled = compilePolicy([...candidates].reverse(), quorum);
    expect(forward.policy_version).toBe(shuffled.policy_version);
    expect(canonicalJson(forward.rule)).toBe(canonicalJson(shuffled.rule));
  });
  it("repeated compiles are byte-identical (no hidden state)", () => {
    const candidates: RuleCandidate[] = [{ scope: "content_type", rule: parsePolicyRule(adminOnly) }];
    const first = compilePolicy(candidates, quorum);
    for (let i = 0; i < 5; i += 1) {
      expect(compilePolicy(candidates, quorum)).toEqual(first);
    }
  });
  it("no candidates => fail-closed immediate baseline with a stable version", () => {
    const empty = compilePolicy([], quorum);
    expect(empty.rule.mode).toBe("immediate");
    expect(empty.policy_version).toBe(compilePolicy([], { adminCount: 0, observedParticipants: 0, eligibleParticipants: 0 }).policy_version);
    expect(empty.policy_version).toBe(policyHash(parsePolicyRule({ mode: "immediate", allowVeto: false })));
  });
});

describe("resolvePrecedence (D4: topic > content_type > account > workspace)", () => {
  it("picks the most specific scope", () => {
    const all: RuleCandidate[] = [
      { scope: "workspace", rule: parsePolicyRule(immediate) },
      { scope: "account", rule: parsePolicyRule(adminOnly) },
      { scope: "content_type", rule: parsePolicyRule(adminOnly) },
      { scope: "topic", rule: parsePolicyRule(quorumRule) },
    ];
    expect(resolvePrecedence(all).scope).toBe("topic");
    expect(resolvePrecedence(all.filter((c) => c.scope !== "topic")).scope).toBe("content_type");
    expect(resolvePrecedence(all.filter((c) => c.scope === "account" || c.scope === "workspace")).scope).toBe("account");
    expect(resolvePrecedence(all.filter((c) => c.scope === "workspace")).scope).toBe("workspace");
  });
  it("whole-block replacement: the winner's rule IS the effective policy", () => {
    const winner = resolvePrecedence([
      { scope: "workspace", rule: parsePolicyRule(quorumRule) },
      { scope: "topic", rule: parsePolicyRule(adminOnly) },
    ]);
    expect(winner.rule.mode).toBe("admin_only");
    expect(winner.rule).not.toHaveProperty("arms");
  });
});

describe("parsePolicyRule validation (400s, never 500s)", () => {
  it("rejects malformed shapes", () => {
    const bad: unknown[] = [
      null,
      "immediate",
      { mode: "nope" },
      { mode: "quorum" }, // no arms
      { mode: "quorum", arms: [] },
      { mode: "quorum", arms: [{ kind: "admins", x: 0 }] },
      { mode: "quorum", arms: [{ kind: "admins", x: 2 }], timebox: { duration: "2 hours", onExpire: "reject" } },
      { mode: "quorum", arms: [{ kind: "admins", x: 2 }] }, // no timebox
      { mode: "admin_only", arms: [{ kind: "participants", x: 2 }], timebox: { duration: "PT1H", onExpire: "reject" } },
      { mode: "immediate", arms: [{ kind: "admins", x: 1 }] },
      { mode: "quorum", arms: [{ kind: "admins", x: 2, of: "observed" }], timebox: { duration: "PT1H", onExpire: "reject" } },
      { mode: "quorum", arms: [{ kind: "participants", x: 2 }], timebox: { duration: "PT1H", onExpire: "maybe" } },
      { mode: "quorum", arms: [{ kind: "admins", x: 2 }], join: "xor", timebox: { duration: "PT1H", onExpire: "reject" } },
      { mode: "quorum", arms: [{ kind: "admins", x: 2 }], anonymity: "secret", timebox: { duration: "PT1H", onExpire: "reject" } },
      { mode: "quorum", arms: [{ kind: "admins", x: 2 }], minDwellSeconds: -1, timebox: { duration: "PT1H", onExpire: "reject" } },
      { version: 2, mode: "immediate" },
    ];
    for (const input of bad) {
      expect(() => parsePolicyRule(input), JSON.stringify(input)).toThrow();
    }
  });
  it("accepts the full §1a surface and normalises defaults", () => {
    const rule = parsePolicyRule(quorumRule);
    expect(rule).toMatchObject({
      version: 1,
      mode: "quorum",
      join: "all",
      allowVeto: true,
      anonymity: "named",
      allowSelfApproval: false,
      resetOnChange: true,
      dryRun: false,
      minDwellSeconds: 0,
    });
    expect(rule.arms).toHaveLength(2);
    expect(rule.timebox).toEqual({ duration: "PT2H", onExpire: "reject" });
  });
  it("ISO-8601 duration shapes accepted include days/minutes/seconds", () => {
    for (const duration of ["PT30M", "PT45S", "P1DT12H", "PT2H30M"]) {
      expect(() => parsePolicyRule({ mode: "quorum", arms: [{ kind: "admins", x: 1 }], timebox: { duration, onExpire: "escalateOwner" } })).not.toThrow();
    }
  });
});