import { SuaveplanError } from "@suaveplan/error";

/** Standard RFC 7807 content-type. */
export const PROBLEM_JSON_CONTENT_TYPE = "application/problem+json";

/**
 * Minimal structural Hono context surface relied on by
 * {@link respondProblemJson}. Declared as an interface so the renderer
 * does not couple to a specific Hono version.
 */
export interface HonoLike {
    header(name: string, value: string): void;
    body(data: string, status: number): Response;
}

/** RFC 7807 problem-details body. */
export interface ProblemDetails {
    readonly type: string;
    readonly title: string;
    readonly status: number;
    readonly detail: string;
    readonly code?: string;
    readonly [key: string]: unknown;
}

/**
 * Convert an arbitrary error into an RFC 7807 problem-details body and
 * write it to the supplied Hono context. `SuaveplanError` subclasses
 * surface their `code` and read `context.statusCode` for the HTTP code;
 * plain `Error` and unknown throwables fall through to a generic
 * `500 Internal Server Error`.
 */
export function respondProblemJson(c: HonoLike, err: unknown): Response {
    const body = renderProblem(err);
    c.header("content-type", PROBLEM_JSON_CONTENT_TYPE);
    return c.body(JSON.stringify(body), body.status);
}

/**
 * Pure render — kept separate from {@link respondProblemJson} so the
 * shape can be asserted in tests that do not construct a Hono context.
 */
export function renderProblem(err: unknown): ProblemDetails {
    if (err instanceof SuaveplanError) {
        const ctx = err.context as { statusCode?: number } | undefined;
        const status =
            typeof ctx?.statusCode === "number" && ctx.statusCode >= 400
                ? ctx.statusCode
                : 500;
        return {
            type: `urn:suaveplan:error:${err.code.toLowerCase()}`,
            title: err.name,
            status,
            detail: err.message,
            code: err.code,
        };
    }
    if (err instanceof Error) {
        return {
            type: "urn:suaveplan:error:internal",
            title: err.name || "InternalError",
            status: 500,
            detail: err.message || "Internal Server Error",
        };
    }
    return {
        type: "urn:suaveplan:error:internal",
        title: "InternalError",
        status: 500,
        detail: "Internal Server Error",
    };
}