/**
 * Knowledge extraction service — extracts relationships and definitions from text chunks.
 *
 * A FlowProcessor that:
 * 1. Consumes Chunk messages
 * 2. Uses prompt service + LLM to extract relationships and definitions
 * 3. Converts extractions into RDF triples and entity contexts
 * 4. Emits Triples and EntityContexts messages
 *
 * Python reference: trustgraph-flow/trustgraph/extract/knowledge/service.py
 */

import {
  makeFlowProcessor,
  makeConsumerSpec,
  makeProducerSpec,
  makeRequestResponseSpec,
  makeFlowProcessorProgram,
  type ProcessorConfig,
  type FlowProcessorRuntime,
  type FlowContext,
  type Chunk,
  type Triples,
  type EntityContexts,
  type EntityContext,
  type PromptRequest,
  type PromptResponse,
  type TextCompletionRequest,
  type TextCompletionResponse,
  type Triple,
  type Term,
  type FlowResourceNotFoundError,
  type MessagingDeliveryError,
  type EffectRequestResponse,
  type Spec,
} from "@trustgraph/base";
import { NodeRuntime } from "@effect/platform-node";
import { Effect, Layer, ManagedRuntime } from "effect";
import * as O from "effect/Option";
import * as S from "effect/Schema";

// Well-known RDF/SKOS IRIs
const RDFS_LABEL = "http://www.w3.org/2000/01/rdf-schema#label";
const SKOS_DEFINITION = "http://www.w3.org/2004/02/skos/core#definition";

const ExtractedRelationship = S.Struct({
  subject: S.String,
  predicate: S.String,
  object: S.String,
});
type ExtractedRelationship = typeof ExtractedRelationship.Type;

const ExtractedRelationshipsFromJson = S.Array(ExtractedRelationship).pipe(S.fromJsonString);
const decodeExtractedRelationships = S.decodeUnknownOption(ExtractedRelationshipsFromJson);

const ExtractedDefinition = S.Struct({
  entity: S.String,
  definition: S.String,
});
type ExtractedDefinition = typeof ExtractedDefinition.Type;

const ExtractedDefinitionsFromJson = S.Array(ExtractedDefinition).pipe(S.fromJsonString);
const decodeExtractedDefinitions = S.decodeUnknownOption(ExtractedDefinitionsFromJson);

type KnowledgeExtractHandlerError =
  | FlowResourceNotFoundError
  | MessagingDeliveryError;

type PromptClient = EffectRequestResponse<PromptRequest, PromptResponse>;
type LlmClient = EffectRequestResponse<TextCompletionRequest, TextCompletionResponse>;

const ExtractTriplesProducer = makeProducerSpec<Triples>("extract-triples");
const ExtractEntityContextsProducer = makeProducerSpec<EntityContexts>("extract-entity-contexts");
const PromptClientSpec = makeRequestResponseSpec<PromptRequest, PromptResponse>(
  "prompt-client",
  "prompt-request",
  "prompt-response",
);
const LlmClientSpec = makeRequestResponseSpec<TextCompletionRequest, TextCompletionResponse>(
  "llm-client",
  "text-completion-request",
  "text-completion-response",
);

const requestPrompt = Effect.fn("KnowledgeExtract.requestPrompt")(function* (
  promptClient: PromptClient,
  name: string,
  text: string,
) {
  return yield* promptClient.request(
    { name, variables: { text } },
    { timeoutMs: 10_000 },
  );
});

const requestCompletion = Effect.fn("KnowledgeExtract.requestCompletion")(function* (
  llmClient: LlmClient,
  prompt: PromptResponse,
) {
  return yield* llmClient.request(
    { system: prompt.system, prompt: prompt.prompt },
    { timeoutMs: 120_000 },
  );
});

const extractRelationships = Effect.fn("KnowledgeExtract.extractRelationships")(function* (
  promptClient: PromptClient,
  llmClient: LlmClient,
  text: string,
) {
  const relPrompt = yield* requestPrompt(promptClient, "extract-relationships", text);
  if (relPrompt.error !== undefined) return null;

  for (let attempt = 0; attempt < 3; attempt++) {
    const relCompletion = yield* requestCompletion(llmClient, relPrompt);

    if (relCompletion.error !== undefined || relCompletion.response.length === 0) {
      break;
    }

    const relationships = parseRelationshipsResponse(relCompletion.response);
    if (relationships !== null) return relationships;

    yield* Effect.logWarning(
      `[KnowledgeExtract] Relationship parse failed, attempt ${attempt + 1}/3`,
    );
  }

  return null;
});

const extractDefinitions = Effect.fn("KnowledgeExtract.extractDefinitions")(function* (
  promptClient: PromptClient,
  llmClient: LlmClient,
  text: string,
) {
  const defPrompt = yield* requestPrompt(promptClient, "extract-definitions", text);
  if (defPrompt.error !== undefined) return null;

  for (let attempt = 0; attempt < 3; attempt++) {
    const defCompletion = yield* requestCompletion(llmClient, defPrompt);

    if (defCompletion.error !== undefined || defCompletion.response.length === 0) {
      break;
    }

    const definitions = parseDefinitionsResponse(defCompletion.response);
    if (definitions !== null) return definitions;

    yield* Effect.logWarning(
      `[KnowledgeExtract] Definition parse failed, attempt ${attempt + 1}/3`,
    );
  }

  return null;
});

const onKnowledgeExtractMessage = Effect.fn("KnowledgeExtractService.onMessage")(function* (
  msg: Chunk,
  properties: Record<string, string>,
  flowCtx: FlowContext,
): Effect.fn.Return<void, KnowledgeExtractHandlerError> {
  const requestId = properties.id;
  if (requestId === undefined || requestId.length === 0) return;

  const text = msg.chunk;
  if (text.trim().length === 0) return;

  const promptClient = yield* flowCtx.flow.requestorEffect(PromptClientSpec);
  const llmClient = yield* flowCtx.flow.requestorEffect(LlmClientSpec);
  const triplesProducer = yield* flowCtx.flow.producerEffect(ExtractTriplesProducer);
  const entityContextsProducer = yield* flowCtx.flow.producerEffect(ExtractEntityContextsProducer);

  const allTriples: Triple[] = [];
  const allEntityContexts: EntityContext[] = [];

  const relationships = yield* extractRelationships(promptClient, llmClient, text).pipe(
    Effect.catch((error: unknown) =>
      Effect.logError("[KnowledgeExtract] Relationship extraction failed", {
        error: error instanceof Error ? error.message : String(error),
      }).pipe(Effect.as(null)),
    ),
  );

  if (relationships !== null) {
    for (const rel of relationships) {
      if (
        rel.subject.length === 0 ||
        rel.predicate.length === 0 ||
        rel.object.length === 0
      ) {
        continue;
      }

      const subjectIri = toEntityIri(rel.subject);
      const predicateIri = toEntityIri(rel.predicate);
      const objectIri = toEntityIri(rel.object);

      allTriples.push({ s: subjectIri, p: predicateIri, o: objectIri });
      allTriples.push({
        s: subjectIri,
        p: iriTerm(RDFS_LABEL),
        o: literalTerm(rel.subject),
      });
      allTriples.push({
        s: predicateIri,
        p: iriTerm(RDFS_LABEL),
        o: literalTerm(rel.predicate),
      });
      allTriples.push({
        s: objectIri,
        p: iriTerm(RDFS_LABEL),
        o: literalTerm(rel.object),
      });

      allEntityContexts.push({
        entity: subjectIri,
        context: text,
        chunkId: msg.documentId,
      });
      allEntityContexts.push({
        entity: objectIri,
        context: text,
        chunkId: msg.documentId,
      });
    }

    yield* Effect.log(`[KnowledgeExtract] Extracted ${relationships.length} relationships`);
  }

  const definitions = yield* extractDefinitions(promptClient, llmClient, text).pipe(
    Effect.catch((error: unknown) =>
      Effect.logError("[KnowledgeExtract] Definition extraction failed", {
        error: error instanceof Error ? error.message : String(error),
      }).pipe(Effect.as(null)),
    ),
  );

  if (definitions !== null) {
    for (const def of definitions) {
      if (def.entity.length === 0 || def.definition.length === 0) continue;

      const entityIri = toEntityIri(def.entity);

      allTriples.push({
        s: entityIri,
        p: iriTerm(SKOS_DEFINITION),
        o: literalTerm(def.definition),
      });
      allTriples.push({
        s: entityIri,
        p: iriTerm(RDFS_LABEL),
        o: literalTerm(def.entity),
      });

      allEntityContexts.push({
        entity: entityIri,
        context: text,
        chunkId: msg.documentId,
      });
    }

    yield* Effect.log(`[KnowledgeExtract] Extracted ${definitions.length} definitions`);
  }

  if (allTriples.length > 0) {
    yield* triplesProducer.send(requestId, {
      metadata: msg.metadata,
      triples: allTriples,
    });
  }

  if (allEntityContexts.length > 0) {
    yield* entityContextsProducer.send(requestId, {
      metadata: msg.metadata,
      entities: allEntityContexts,
    });
  }
});

export const makeKnowledgeExtractSpecs = (): ReadonlyArray<Spec<never>> => [
  makeConsumerSpec<Chunk, KnowledgeExtractHandlerError>(
    "extract-input",
    onKnowledgeExtractMessage,
  ),
  ExtractTriplesProducer,
  ExtractEntityContextsProducer,
  PromptClientSpec,
  LlmClientSpec,
];

export type KnowledgeExtractService = FlowProcessorRuntime;

export function makeKnowledgeExtractService(config: ProcessorConfig): KnowledgeExtractService {
  const service = makeFlowProcessor(config, {
    specifications: makeKnowledgeExtractSpecs(),
  });
  Effect.runSync(Effect.log("[KnowledgeExtract] Service initialized"));
  return service;
}

export const KnowledgeExtractService = makeKnowledgeExtractService;

// ---------- Helpers ----------

function toEntityIri(name: string): Term {
  const slug = encodeURIComponent(name.toLowerCase().replace(/\s+/g, "-"));
  return {
    type: "IRI",
    iri: `http://trustgraph.ai/e/${slug}`,
  };
}

function iriTerm(iri: string): Term {
  return { type: "IRI", iri };
}

function literalTerm(value: string): Term {
  return { type: "LITERAL", value };
}

/**
 * Parse JSON from LLM output, handling markdown code fences and malformed output.
 * Uses progressive fallback: direct parse, array extraction, truncated array repair, single object wrap.
 */
export function parseJsonResponse<T>(raw: string): T | null {
  const decodeJson = S.decodeUnknownOption(S.UnknownFromJsonString);
  for (const candidate of jsonCandidates(raw)) {
    const decoded = decodeJson(candidate);
    if (O.isSome(decoded)) return decoded.value as T;
  }

  Effect.runSync(Effect.logWarning("[KnowledgeExtract] Failed to parse JSON from LLM response", {
    response: raw.slice(0, 300),
  }));
  return null;
}

function parseRelationshipsResponse(raw: string): ReadonlyArray<ExtractedRelationship> | null {
  for (const candidate of jsonCandidates(raw)) {
    const decoded = decodeExtractedRelationships(candidate);
    if (O.isSome(decoded)) return decoded.value;
  }
  Effect.runSync(Effect.logWarning("[KnowledgeExtract] Failed to parse relationships from LLM response", {
    response: raw.slice(0, 300),
  }));
  return null;
}

function parseDefinitionsResponse(raw: string): ReadonlyArray<ExtractedDefinition> | null {
  for (const candidate of jsonCandidates(raw)) {
    const decoded = decodeExtractedDefinitions(candidate);
    if (O.isSome(decoded)) return decoded.value;
  }
  Effect.runSync(Effect.logWarning("[KnowledgeExtract] Failed to parse definitions from LLM response", {
    response: raw.slice(0, 300),
  }));
  return null;
}

function jsonCandidates(raw: string): ReadonlyArray<string> {
  const candidates: string[] = [];
  let cleaned = raw.trim();
  const fenceMatch = cleaned.match(/^```(?:json)?\s*\n?([\s\S]*?)\n?```$/);
  if (fenceMatch !== null) {
    cleaned = (fenceMatch[1] ?? "").trim();
  }

  candidates.push(cleaned);

  const arrayMatch = cleaned.match(/\[[\s\S]*\]/);
  if (arrayMatch !== null) {
    candidates.push(arrayMatch[0]);

    const partial = arrayMatch[0];
    const lastBrace = partial.lastIndexOf("}");
    if (lastBrace > 0) {
      candidates.push(partial.slice(0, lastBrace + 1) + "]");
    }
  }

  const objMatch = cleaned.match(/\{[\s\S]*?\}/);
  if (objMatch !== null) {
    candidates.push(`[${objMatch[0]}]`);
  }

  return candidates;
}

export const program = makeFlowProcessorProgram({
  id: "knowledge-extract",
  specs: () => makeKnowledgeExtractSpecs(),
});

const knowledgeExtractRuntime = ManagedRuntime.make(Layer.empty);

export function run(): Promise<void> {
  return knowledgeExtractRuntime.runPromise(program);
}

export function runMain(): void {
  NodeRuntime.runMain(program);
}