import { describe, expect, it } from "@suaveplan/testing/runner";
import { RouterError } from "../error-codes/error-codes.js";
import {
    composeMiddleware,
    type Middleware,
} from "../middleware/middleware.js";
import { MapHeaders, type RouterRequest } from "../request/request.js";
import { jsonResponse } from "../response/response.js";
import type { Router } from "../router/router.js";
import type { BlueGreenSlot, SlotHandler } from "../slot/slot.js";

/**
 * Factory bundle the conformance harness consumes — a concrete adapter
 * supplies one of these and the harness exercises every required case.
 */
export interface RouterConformanceFactory {
    /** Build a fresh `Router` (or adapter-equivalent) for each test. */
    readonly router: () => Router;
    /**
     * Build a fresh `BlueGreenSlot` — adapter may use the reference impl or
     * its own implementation. The harness passes `(plugin, handler)`.
     */
    readonly slot: (plugin: string, handler: SlotHandler) => BlueGreenSlot;
    /** Display label used in test names. */
    readonly label: string;
}

/** Noop `OtelSpanLike` — usable in test scenarios that don't assert on spans. */
export function makeNoopSpan(): RouterRequest["span"] {
    return {
        setAttribute() {
            /* noop */
        },
        setStatus() {
            /* noop */
        },
        recordException() {
            /* noop */
        },
        end() {
            /* noop */
        },
    };
}

/** Build a synthetic `RouterRequest` — the harness uses this internally. */
export function makeFixtureRequest(
    overrides: Partial<RouterRequest> = {}
): RouterRequest {
    return {
        method: "GET",
        url: "/x",
        headers: new MapHeaders(),
        body: undefined,
        params: {},
        query: {},
        tenantId: "t" as never,
        principal: null,
        requestId: "r",
        span: makeNoopSpan(),
        ...overrides,
    };
}

function makeReq(): RouterRequest {
    return makeFixtureRequest();
}

/**
 * Runs the canonical conformance suite against the supplied factory.
 *
 * Every adapter in Stages 4-7 (`api-router-hono`, `api-router-in-memory`,
 * the worker-bridge router) MUST pass this suite. The harness exercises:
 *   - every verb method
 *   - `mount(prefix, child)` rewriting
 *   - middleware chain ordering via `composeMiddleware`
 *   - route collision detection
 *   - `BlueGreenSlot` lifecycle (set → flip → drain → dispose)
 *   - param parsing
 *   - error propagation
 */
export function runRouterConformance(factory: RouterConformanceFactory): void {
    describe(`Router conformance — ${factory.label}`, () => {
        it("declares every verb method", { timeout: 5000 }, () => {
            const r = factory.router();
            r.get("/g", () => null);
            r.post("/p", () => null);
            r.put("/u", () => null);
            r.patch("/pa", () => null);
            r.delete("/d", () => null);
            r.head("/h", () => null);
            r.options("/o", () => null);
            expect(r.match("GET", "/g")).not.toBeNull();
            expect(r.match("POST", "/p")).not.toBeNull();
            expect(r.match("PUT", "/u")).not.toBeNull();
            expect(r.match("PATCH", "/pa")).not.toBeNull();
            expect(r.match("DELETE", "/d")).not.toBeNull();
            expect(r.match("HEAD", "/h")).not.toBeNull();
            expect(r.match("OPTIONS", "/o")).not.toBeNull();
        });

        it("rewrites paths under mount(prefix, sub)", { timeout: 5000 }, () => {
            const parent = factory.router();
            const child = factory.router();
            child.get("/invoices", () => null);
            parent.mount("/billing", child);
            expect(parent.match("GET", "/billing/invoices")).not.toBeNull();
        });

        it("composes middleware in declared order", {
            timeout: 5000,
        }, async () => {
            const trace: string[] = [];
            const a: Middleware = async (_, next) => {
                trace.push("a");
                const r = await next();
                trace.push("a-out");
                return r;
            };
            const b: Middleware = async (_, next) => {
                trace.push("b");
                const r = await next();
                trace.push("b-out");
                return r;
            };
            const composed = composeMiddleware([a, b]);
            await composed(makeReq(), async () => {
                trace.push("terminal");
                return jsonResponse(200, null);
            });
            expect(trace).toEqual(["a", "b", "terminal", "b-out", "a-out"]);
        });

        it("rejects same-plugin route collisions", { timeout: 5000 }, () => {
            const r = factory.router();
            r.get("/x", () => null);
            expect(() => r.get("/x", () => null)).toThrow(RouterError);
        });

        it("parses path parameters", { timeout: 5000 }, () => {
            const r = factory.router();
            r.get("/users/:id", () => null);
            const m = r.match("GET", "/users/u_42");
            expect(m?.params).toEqual({ id: "u_42" });
        });

        it("supports blue-green slot lifecycle", {
            timeout: 5000,
        }, async () => {
            const slot = factory.slot("conf", () => "v1");
            slot.setShadow(() => "v2");
            const draining = slot.flip();
            expect(slot.live.slotId).not.toBe(draining.slotId);
            await expect(
                slot.dispose(draining.slotId, { timeoutMs: 100 })
            ).resolves.toBeUndefined();
        });

        it("flip with no shadow throws SLOT_FLIP_FAILED", {
            timeout: 5000,
        }, () => {
            const slot = factory.slot("conf", () => null);
            expect(() => slot.flip()).toThrow(RouterError);
        });

        it("propagates errors through the middleware chain", {
            timeout: 5000,
        }, async () => {
            const boom: Middleware = async () => {
                throw new Error("conformance-boom");
            };
            const composed = composeMiddleware([boom]);
            await expect(
                composed(makeReq(), async () => jsonResponse(200, null))
            ).rejects.toThrow(/conformance-boom/);
        });
    });
}