/**
 * G7 — Serialization round-trip of a complete rule
 *
 * Pararules origin: pararules uses staticRuleset (tests/test3.nim) for
 * compile-time rule serialization. Our engine equivalent is the
 * serialize/deserialize JSON round-trip per SPEC §JSON Rule Schema:
 *   - Rules are pure data (no closures, no eval)
 *   - Handlers are referenced by name and resolved against a HandlerRegistry
 *   - serialize() → JSON-safe object → JSON.stringify → JSON.parse → deserialize()
 *     produces a structurally identical RuleDefinition
 *
 * This tests the full pipeline including Zod schema validation.
 */
import { describe, it, expect } from "vitest";
import { serialize, deserialize, RULE_SCHEMA_V1 } from "../../src/serialize.js";
import { defineRule, v } from "../../src/builder.js";
import { HandlerRegistry, UnknownHandlerError } from "../../src/registry.js";
import type { EntityId } from "../../src/schema.js";

function makeRegistry(...names: string[]): HandlerRegistry {
  const reg = new HandlerRegistry();
  for (const name of names) {
    reg.register(name, () => {});
  }
  return reg;
}

describe("G7 — serialization round-trip", () => {
  it("serialize + JSON round-trip + deserialize produces equivalent RuleDefinition", () => {
    const registry = makeRegistry("myHandler");

    const rule = defineRule({
      name: "myRule",
      salience: 5,
      what: [
        { id: null, attr: "Health", binding: v("hp"), idBinding: v("eid") },
        { id: null, attr: "Position", binding: v("pos") },
      ],
      handler: "myHandler",
      registry,
    });

    // Serialize → JSON → deserialize
    const serialized = serialize(rule);
    const json = JSON.stringify(serialized);
    const parsed = JSON.parse(json) as unknown;
    const restored = deserialize(parsed, registry);

    // Core identity preserved
    expect(restored.name).toBe(rule.name);
    expect(restored.salience).toBe(rule.salience);
    expect(restored.handler).toBe(rule.handler);
    expect(restored.conditions).toHaveLength(rule.conditions.length);

    // Condition details preserved
    const c0 = restored.conditions[0];
    expect(c0?.id).toBe(null);
    expect(c0?.attr).toBe("Health");
    expect(c0?.binding?.name).toBe("hp");
    expect(c0?.idBinding?.name).toBe("eid");

    const c1 = restored.conditions[1];
    expect(c1?.attr).toBe("Position");
    expect(c1?.binding?.name).toBe("pos");
    expect(c1?.idBinding).toBeUndefined();
  });

  it("rule with specific entity id survives round-trip", () => {
    const registry = makeRegistry("handler");
    const specificId = 42 as EntityId;

    const rule = defineRule({
      name: "specificRule",
      salience: 0,
      what: [{ id: specificId, attr: "Active", binding: v("active") }],
      handler: "handler",
      registry,
    });

    const serialized = serialize(rule);
    const restored = deserialize(JSON.parse(JSON.stringify(serialized)), registry);

    expect(restored.conditions[0]?.id).toBe(42);
  });

  it("rule with handlerArgs survives round-trip", () => {
    const registry = makeRegistry("handler");

    const rule = defineRule({
      name: "argsRule",
      salience: 0,
      what: [{ id: null, attr: "X", binding: v("x") }],
      handler: "handler",
      handlerArgs: ["threshold", 50, true],
      registry,
    });

    const serialized = serialize(rule);
    const restored = deserialize(JSON.parse(JSON.stringify(serialized)), registry);

    expect(restored.handlerArgs).toEqual(["threshold", 50, true]);
  });

  it("salience defaults to 0 when omitted in serialized form", () => {
    const registry = makeRegistry("h");
    const raw = { name: "noSalience", handler: "h", conditions: [] };
    const restored = deserialize(raw, registry);
    expect(restored.salience).toBe(0);
  });

  it("deserialize throws UnknownHandlerError for unregistered handler", () => {
    const emptyRegistry = new HandlerRegistry();
    const json = { name: "r", handler: "missing", conditions: [] };
    expect(() => deserialize(json, emptyRegistry)).toThrow(UnknownHandlerError);
  });

  it("RULE_SCHEMA_V1 validates structure with Zod", () => {
    const valid = { name: "r", handler: "h", conditions: [], salience: 0 };
    const parsed = RULE_SCHEMA_V1.safeParse(valid);
    expect(parsed.success).toBe(true);

    const invalid = { name: "", handler: "h" }; // empty name fails min(1)
    const badParsed = RULE_SCHEMA_V1.safeParse(invalid);
    expect(badParsed.success).toBe(false);
  });

  it("serialize produces plain JSON-safe values (no functions, no undefined)", () => {
    const registry = makeRegistry("h");
    const rule = defineRule({
      name: "plain",
      salience: 1,
      what: [{ id: null, attr: "X", binding: v("x") }],
      handler: "h",
      registry,
    });

    const serialized = serialize(rule);
    // Must round-trip cleanly through JSON without loss
    const jsonStr = JSON.stringify(serialized);
    expect(typeof jsonStr).toBe("string");
    const reparsed = JSON.parse(jsonStr) as Record<string, unknown>;
    expect(reparsed["name"]).toBe("plain");
    expect(reparsed["salience"]).toBe(1);
    expect(Array.isArray(reparsed["conditions"])).toBe(true);
  });
});