import { z } from "zod";

import { consultationDomainSchema } from "./consultation-domain-registry.ts";

/**
 * Closed, non-PII observability contract for Agent runs.
 *
 * There is intentionally no free-form metadata bag. Raw input/output text,
 * prompts, messages, birth data, names, email addresses, secrets, API keys,
 * provider payloads, stack traces and internal filesystem paths are not fields
 * in this schema. Every object is strict, so unknown fields fail closed.
 */

const opaqueIdSchema = z.string()
  .min(1)
  .max(128)
  .regex(/^[A-Za-z0-9][A-Za-z0-9._:-]*$/, "invalid opaque identifier");

const machineValueSchema = z.string()
  .min(1)
  .max(128)
  .regex(/^[A-Za-z0-9][A-Za-z0-9._:+-]*$/, "invalid machine value");

const machineCodeSchema = z.string()
  .min(1)
  .max(80)
  .regex(/^[a-z][a-z0-9._-]*$/, "invalid machine code");

const durationMsSchema = z.number().int().min(0).max(7 * 24 * 60 * 60 * 1000);
const countSchema = z.number().int().min(0).max(1_000_000);
const tokenCountSchema = z.number().int().min(0).max(1_000_000_000);

export const agentObservabilityStepStatuses = [
  "completed",
  "failed",
  "cancelled",
  "skipped",
] as const;

export const billingSettlementResults = [
  "completed",
  "cancelled",
  "failed",
  "not_applicable",
] as const;

export type AgentBillingSettlementResult = (typeof billingSettlementResults)[number];
export type AgentSettlementResult = Exclude<AgentBillingSettlementResult, "not_applicable">;

/**
 * Closed vocabulary for why the model stopped stepping. These are the provider
 * finish reasons plus the two Mastra adds; anything else normalizes to
 * `unknown` so an unrecognized provider string can never become a log field.
 *
 * `tool-calls` on a run that produced no answer means the step budget ran out
 * while the model still wanted to call a tool, which is otherwise only
 * inferable from the recorded step list.
 */
export const agentModelFinishReasons = [
  "stop",
  "length",
  "content-filter",
  "tool-calls",
  "error",
  "other",
  "tripwire",
  "retry",
  "unknown",
] as const;

export type AgentModelFinishReason = (typeof agentModelFinishReasons)[number];

const knownModelFinishReasons = new Set<string>(agentModelFinishReasons);

export function toAgentModelFinishReason(value: unknown): AgentModelFinishReason {
  return typeof value === "string" && knownModelFinishReasons.has(value)
    ? value as AgentModelFinishReason
    : "unknown";
}

export type AgentSettlementTelemetryOutcome = Readonly<{
  billingSettlementResult: AgentSettlementResult;
  errorCode?: string;
}>;

export function settlementTelemetryOutcome(
  settlementResult: AgentSettlementResult,
  errorCode?: string,
): AgentSettlementTelemetryOutcome {
  if (settlementResult === "failed") {
    return {
      billingSettlementResult: "failed",
      errorCode: "settlement_failed",
    };
  }
  return {
    billingSettlementResult: settlementResult,
    ...(errorCode === undefined ? {} : { errorCode }),
  };
}

export const agentObservabilityToolCallSchema = z.object({
  name: machineCodeSchema,
  durationMs: durationMsSchema,
  status: z.enum(agentObservabilityStepStatuses),
  // Closed classification of why the call failed. Never upstream error text.
  failureCode: machineCodeSchema.optional(),
}).strict().readonly();

export const agentObservabilityContractPhaseSchema = z.object({
  phase: machineCodeSchema,
  durationMs: durationMsSchema.optional(),
  status: z.enum(agentObservabilityStepStatuses),
}).strict().readonly();

export const agentObservabilityEventSchema = z.object({
  runId: opaqueIdSchema.optional(),
  requestId: opaqueIdSchema.optional(),
  sessionId: opaqueIdSchema.optional(),
  caseId: opaqueIdSchema.optional(),

  agentVersion: machineValueSchema.optional(),
  skillVersion: machineValueSchema.optional(),
  modelVersion: machineValueSchema.optional(),
  policyVersion: machineValueSchema.optional(),

  toolCalls: z.array(agentObservabilityToolCallSchema).max(64).optional(),
  contractPhases: z.array(agentObservabilityContractPhaseSchema).max(64).optional(),
  retryCount: z.number().int().min(0).max(100).optional(),
  errorCode: machineCodeSchema.optional(),
  // Why the model stopped, and how many model steps the run consumed across
  // every attempt. Both are enum-like machine values, never provider text.
  modelFinishReason: z.enum(agentModelFinishReasons).optional(),
  modelStepCount: countSchema.optional(),
  // How many reference documents the model opened after loading the skill, and how many strict-method
  // sections the server delivered with the evidence. Both are needed to read the other: zero reads is
  // only a gap in the answer's method if nothing was delivered either.
  skillReferenceReads: countSchema.optional(),
  methodologySections: countSchema.optional(),

  inputTokens: tokenCountSchema.optional(),
  outputTokens: tokenCountSchema.optional(),
  evidenceCount: countSchema.optional(),
  claimCount: countSchema.optional(),
  sectionCount: countSchema.optional(),
  themeCoverage: z.array(consultationDomainSchema).max(10).optional(),

  reportJobDurationMs: durationMsSchema.optional(),
  reportJobPeakMemoryBytes: z.number().int().min(0).max(Number.MAX_SAFE_INTEGER).optional(),
  billingSettlementResult: z.enum(billingSettlementResults).optional(),
}).strict().refine(
  (event) => Boolean(event.runId || event.requestId || event.sessionId || event.caseId),
  { message: "at least one controlled identifier is required" },
).readonly();

export type AgentObservabilityEvent = z.infer<typeof agentObservabilityEventSchema>;
export type AgentObservabilitySink = (event: AgentObservabilityEvent) => void;
export type AgentObservabilityLogger = (event: unknown) => AgentObservabilityEvent;

function consoleSink(event: AgentObservabilityEvent): void {
  console.info("[agent-observability]", JSON.stringify(event));
}

export function createAgentObservabilityLogger(
  sink: AgentObservabilitySink = consoleSink,
): AgentObservabilityLogger {
  return (event) => {
    const parsed = agentObservabilityEventSchema.parse(event);
    try {
      sink(parsed);
    } catch {
      // Observability transport failure must not change the business response.
    }
    return parsed;
  };
}

export const logAgentObservability = createAgentObservabilityLogger();

const knownErrorCodes = new Set([
  "runtime_contract_incomplete",
  "empty_answer",
  "calculation_failed",
  "timeout",
  "cancelled",
  "settlement_failed",
]);

export function toAgentObservabilityErrorCode(error: unknown): string {
  if (error instanceof DOMException) {
    if (error.name === "TimeoutError") return "timeout";
    if (error.name === "AbortError") return "cancelled";
  }
  if (error instanceof Error && knownErrorCodes.has(error.message)) return error.message;
  return "calculation_failed";
}