import test from "node:test";
import assert from "node:assert/strict";
import { resolvePolicy } from "./config.ts";
import { buildContextPacket } from "./packet.ts";
import { createEmptyLedger, mergeCandidates, type MemoryCandidate } from "./ledger.ts";

const baseCandidate: Omit<MemoryCandidate, "kind" | "subject" | "text"> = {
  scope: "session",
  sourceEntryId: "seed",
  sourceType: "user",
  timestamp: 1,
  confidence: 1,
};

function estimateTokens(text: string) {
  return Math.ceil(text.length / 4);
}

function memory(candidate: Pick<MemoryCandidate, "kind" | "subject" | "text"> & Partial<Omit<MemoryCandidate, "kind" | "subject" | "text">>): MemoryCandidate {
  return {
    ...baseCandidate,
    ...candidate,
    sourceEntryId: candidate.sourceEntryId ?? candidate.subject,
  };
}

function buildPolicy(packetTokenCap: number) {
  return {
    ...resolvePolicy({ mode: "balanced", contextWindow: 200_000 }),
    packetTokenCap,
  };
}

test("buildContextPacket keeps top-ranked facts from a section when the cap is tight", () => {
  const expected = [
    "## Active goal",
    "- Keep packets compact.",
    "",
    "## Constraints",
    "- Preserve the highest-priority constraint.",
    "",
    "## Key decisions",
    "- Render selected sections in stable order.",
  ].join("\n");
  const policy = buildPolicy(estimateTokens(expected));
  const ledger = mergeCandidates(createEmptyLedger(), [
    memory({ kind: "goal", subject: "goal", text: "Keep packets compact." }),
    memory({ kind: "constraint", subject: "constraint-a", text: "Preserve the highest-priority constraint.", confidence: 1, timestamp: 3 }),
    memory({
      kind: "constraint",
      subject: "constraint-b",
      text: "Avoid dropping every constraint just because one extra bullet is too large for a tight packet cap.",
      confidence: 0.6,
      timestamp: 2,
    }),
    memory({
      kind: "decision",
      subject: "decision-a",
      text: "Render selected sections in stable order.",
      confidence: 0.9,
      timestamp: 4,
      sourceType: "assistant",
    }),
  ]);

  const packet = buildContextPacket(ledger, policy);

  assert.equal(packet.text, expected);
  assert.equal(packet.estimatedTokens, policy.packetTokenCap);
});

test("buildContextPacket uses cross-kind weights when only one lower-priority section can fit", () => {
  const expected = [
    "## Active goal",
    "- Keep the agent moving.",
    "",
    "## Current task",
    "- Fix packet trimming.",
  ].join("\n");
  const policy = buildPolicy(estimateTokens(expected));
  const ledger = mergeCandidates(createEmptyLedger(), [
    memory({ kind: "goal", subject: "goal", text: "Keep the agent moving." }),
    memory({
      kind: "decision",
      subject: "decision-a",
      text: "Keep logs concise.",
      confidence: 1,
      timestamp: 2,
      sourceType: "assistant",
    }),
    memory({
      kind: "activeTask",
      subject: "task-a",
      text: "Fix packet trimming.",
      confidence: 1,
      timestamp: 2,
      sourceType: "assistant",
    }),
  ]);

  const packet = buildContextPacket(ledger, policy);

  assert.equal(packet.text, expected);
  assert.equal(packet.estimatedTokens, policy.packetTokenCap);
});

test("buildContextPacket keeps a goal ahead of newer low-priority facts at realistic timestamp scales", () => {
  const expected = [
    "## Active goal",
    "- Keep the agent on track.",
  ].join("\n");
  const policy = buildPolicy(estimateTokens(expected));
  const ledger = mergeCandidates(createEmptyLedger(), [
    memory({ kind: "goal", subject: "goal", text: "Keep the agent on track.", timestamp: 1_000_000 }),
    memory({
      kind: "relevantFile",
      subject: "runtime-file",
      text: "src/runtime.ts",
      timestamp: 10_000_000,
      confidence: 1,
      sourceType: "assistant",
      scope: "branch",
    }),
  ]);

  const packet = buildContextPacket(ledger, policy);

  assert.equal(packet.text, expected);
  assert.equal(packet.estimatedTokens, policy.packetTokenCap);
});