/** Serializable retrieval configuration. @module dsh-tool-retriever/config */

import z from '@deepseek-ai/schemastery'

/** BM25F weights for deterministic fields extracted from a DSH tool schema. */
export interface FieldWeights {
  /** Canonical tool name and its identifier components. */
  name?: number
  /** Tool description supplied by its owner. */
  description?: number
  /** Property names recursively extracted from the input schema. */
  parameterName?: number
  /** Descriptions, titles, and enum literals from the input schema. */
  parameterDescription?: number
}

/** Public plugin configuration supplied by a DSH profile. */
export interface Config {
  /** Number of candidates returned by `tool_search` (default 8, maximum 32). */
  topK?: number
  /** BM25 term-frequency saturation parameter (default 1.2). */
  bm25K1?: number
  /** BM25 field-length normalization parameter (default 0.75). */
  bm25B?: number
  /** Per-field BM25F weights. */
  fieldWeights?: FieldWeights
}

/** Fully resolved configuration used by the retrieval core. */
export interface ResolvedConfig {
  topK: number
  bm25K1: number
  bm25B: number
  fieldWeights: Required<FieldWeights>
}

const fieldWeightsSchema = z.object({
  name: z.number().min(0).default(4),
  description: z.number().min(0).default(2),
  parameterName: z.number().min(0).default(1.5),
  parameterDescription: z.number().min(0).default(1),
}).default({ name: 4, description: 2, parameterName: 1.5, parameterDescription: 1 })

/** Loader-visible schema for every deployment-varying retrieval choice. */
export const Config: z<Config> = z.object({
  topK: z.number().step(1).min(1).max(32).default(8),
  bm25K1: z.number().min(0.01).max(10).default(1.2),
  bm25B: z.number().min(0).max(1).default(0.75),
  fieldWeights: fieldWeightsSchema,
})

/**
 * Resolve Loader defaults for direct callers and tests.
 * @param config - Validated or programmatically supplied partial configuration.
 * @returns One detached complete retrieval configuration.
 */
export function resolveConfig(config: Config = {}): ResolvedConfig {
  return {
    topK: config.topK ?? 8,
    bm25K1: config.bm25K1 ?? 1.2,
    bm25B: config.bm25B ?? 0.75,
    fieldWeights: {
      name: config.fieldWeights?.name ?? 4,
      description: config.fieldWeights?.description ?? 2,
      parameterName: config.fieldWeights?.parameterName ?? 1.5,
      parameterDescription: config.fieldWeights?.parameterDescription ?? 1,
    },
  }
}