FEDEO/backend/src/mcp/result.ts

import { McpToolResult } from "./types"

const OMIT_ARCHIVED = Symbol("omit-archived")

/** Attach images to a tool payload; they become MCP image content next to the JSON text. */
export const MCP_IMAGES = Symbol("mcp-images")
export type McpImage = { data: string, mimeType: string }
export const withImages = <T extends Record<string, unknown>>(payload: T, images: McpImage[]) =>
    Object.assign(payload, { [MCP_IMAGES]: images })

function omitArchivedRecords(value: unknown): unknown | typeof OMIT_ARCHIVED {
    if (Array.isArray(value)) {
        return value
            .map(omitArchivedRecords)
            .filter((item) => item !== OMIT_ARCHIVED)
    }

    if (!value || typeof value !== "object") return value

    const prototype = Object.getPrototypeOf(value)
    if (prototype !== Object.prototype && prototype !== null) return value

    const record = value as Record<string, unknown>
    if (record.archived === true) return OMIT_ARCHIVED

    return Object.fromEntries(
        Object.entries(record)
            .map(([key, item]) => [key, omitArchivedRecords(item)] as const)
            .filter(([, item]) => item !== OMIT_ARCHIVED),
    )
}

export function asToolResult(payload: unknown): McpToolResult {
    const sanitizedPayload = omitArchivedRecords(payload)
    const resultPayload = sanitizedPayload === OMIT_ARCHIVED ? {} : sanitizedPayload
    const structuredContent =
        resultPayload && typeof resultPayload === "object" && !Array.isArray(resultPayload)
            ? resultPayload as Record<string, unknown>
            : { result: resultPayload }

    const images: McpImage[] = (payload as any)?.[MCP_IMAGES] || []

    return {
        content: [
            {
                type: "text",
                text: JSON.stringify(resultPayload, null, 2),
            },
            ...images.map((image) => ({ type: "image" as const, data: image.data, mimeType: image.mimeType })),
        ],
        structuredContent,
    }
}

export function asToolError(error: unknown): McpToolResult {
    const message = error instanceof Error ? error.message : "Unbekannter Fehler"

    return {
        content: [
            {
                type: "text",
                text: message,
            },
        ],
        isError: true,
        structuredContent: {
            error: message,
        },
    }
}