// lib/adapter.ts — Pi adapter binding (PRD R3-R5; NG-2).
//
// Deliberately dependency-light (type-only imports + node builtins) so the
// hermetic suite can import and exercise the REAL binding against a fake pi
// — including the AC4 red control, which sabotages this file's enforcement
// registration block and proves the same call then passes.
//
// The binding:
//   session_start  (every reason: startup/new/resume/reload/fork — policy may
//                   have changed on disk between sessions) ->
//                   resolve seat role from the launcher-established agent
//                   name -> load trusted manifest -> build application ->
//                   setActiveTools(exact) -> VERIFY getActiveTools() equals
//                   the exact set; any drift at any stage -> fail-closed.
//   tool_call      -> decideToolCall; blocked calls return the stable code.

import { incarnationIdentity } from "./incarnation.ts";
import {
  buildApplication,
  decideToolCall,
  failClosedState,
  statusSnapshot,
  STATUS_TOOL,
  PROPOSAL_TOOL,
  SAFE_READ_TOOLS,
  type EnforcementState,
} from "./enforce.ts";
import { loadTrustedManifest, seatRole, type LoadOutcome, type LoaderIO } from "./loader.ts";
import { createJournal, type Journal, type JournalIO } from "./journal.ts";
import { sanitizeProposal } from "./proposal.ts";
import { publishGoalPolicy, verifyGoalPolicyPublication, type GoalPolicyAttestationV1 } from "./goal-policy.ts";
import { readFileSync, lstatSync, realpathSync } from "node:fs";
import { homedir } from "node:os";

export interface PiToolCallEvent {
  toolName: string;
  input?: unknown;
}

export interface PiLike {
  on(event: "session_start", handler: (event: { reason: string }) => void | Promise<void>): void;
  on(event: "tool_call", handler: (event: PiToolCallEvent) => unknown): void;
  getActiveTools(): string[];
  setActiveTools(names: string[]): void;
  registerTool(tool: Record<string, unknown>): void;
}

export interface AdapterOptions {
  env?: Record<string, string | undefined>;
  io?: LoaderIO;
  journalIO?: JournalIO;
  stateHome?: string;
  incarnationId?: string;
  launchGeneration?: number;
}

function defaultIO(): LoaderIO {
  return {
    readFileSync(path: string): string | Uint8Array { return readFileSync(path); },
    lstatSync,
    realpathSync,
  };
}

function launchGeneration(env: Record<string, string | undefined>, supplied: number | undefined): number | undefined {
  if (supplied !== undefined) return supplied;
  const raw = env.MOSAIC_LAUNCH_GENERATION;
  if (!raw || !/^[1-9][0-9]*$/.test(raw)) return undefined;
  const value = Number(raw);
  return Number.isSafeInteger(value) ? value : undefined;
}

export function bindEnforcement(pi: PiLike, opts: AdapterOptions = {}): void {
  const env = opts.env ?? process.env;
  const io = opts.io ?? defaultIO();
  const incarnationId = opts.incarnationId ?? incarnationIdentity();
  const configuredLaunchGeneration = launchGeneration(env, opts.launchGeneration);
  let enforcement: EnforcementState = { state: "not-applied", incarnationId };
  let activeGoalPolicy: GoalPolicyAttestationV1 | undefined;
  // A version-4 role has exactly one trusted manifest/contract load per
  // incarnation. Reloads reuse this immutable result and never republish.
  let v4Load: Extract<LoadOutcome, { ok: true }> | undefined;
  let v4Published = false;

  const brainHome = env.MOSAIC_BRAIN_HOME || `${homedir()}/.mosaic`;
  const journal: Journal = createJournal({
    incarnationId,
    stateHome: opts.stateHome ?? env.XDG_STATE_HOME,
    io: opts.journalIO,
  });

  pi.registerTool({
    name: STATUS_TOOL,
    label: "Mosaic policy status",
    description:
      "Read-only report of the applied mosaic-core role policy: role, revision, digest, " +
      "active tools, and enforcement state. Cannot modify anything.",
    parameters: { type: "object", properties: {}, additionalProperties: false },
    async execute() {
      return {
        content: [{ type: "text", text: JSON.stringify(statusSnapshot(enforcement, pi.getActiveTools())) }],
        details: {},
      };
    },
  });

  pi.registerTool({
    name: PROPOSAL_TOOL,
    label: "Mosaic improvement proposal",
    description:
      "Record a structured improvement proposal for the mosaic-core role policy. Proposals " +
      "are appended to the per-incarnation journal for coordinator review; they never " +
      "modify manifests, settings, or active tools.",
    parameters: {
      type: "object",
      properties: {
        target: { type: "string", description: "What the proposal concerns: a role, tool, or policy field" },
        summary: { type: "string", description: "One line, at most 500 characters" },
        motivation: { type: "string", description: "Why this improvement matters, at most 2000 characters" },
        evidence: { type: "array", items: { type: "string" }, description: "Optional evidence pointers, at most 8 items of 500 characters" },
      },
      required: ["target", "summary", "motivation"],
      additionalProperties: false,
    },
    async execute(_id: string, params: unknown) {
      const verdict = sanitizeProposal(params);
      if (!verdict.ok) {
        return {
          content: [{ type: "text", text: `proposal rejected (${verdict.reason}${verdict.detail ? `: ${verdict.detail}` : ""}) — recorded nothing` }],
          details: { rejected: verdict.reason },
        };
      }
      try {
        journal.append({ kind: "improvement-proposal", proposal: verdict.proposal });
      } catch {
        // Journal failure: the proposal is NOT recorded, nothing is applied,
        // and the caller sees a fixed message with no raw exception
        return {
          content: [{ type: "text", text: "proposal recording unavailable (journal failure); recorded nothing; nothing applied" }],
          details: { recorded: false, cause: "journal-failure" },
        };
      }
      return {
        content: [{ type: "text", text: `proposal recorded for coordinator review (target: ${verdict.proposal.target}); nothing was applied` }],
        details: { recorded: true },
      };
    },
  });

  // [NG-2 enforcement binding begin]
  // The enforcement surface under AC4's removal red control: exactly these
  // two registrations. Sabotage that deletes this block leaves the status
  // tool but no interception and no application — the same call then passes.
  pi.on("session_start", async () => {
    // Resolve the profile role before entering degraded mode. A known gate role
    // gets status only if its manifest, contract, resolver, or publication
    // fails; it must not inherit generic safe reads or proposal authority.
    const profileRole = seatRole(brainHome, env.MOSAIC_AGENT_NAME, io);
    let roleHint = profileRole ?? undefined;
    // NG4-RECON: enter TRUSTED FAIL-CLOSED BEFORE any platform call.
    // If setActiveTools or getActiveTools throws mid-reconciliation, the
    // previous applied policy does NOT remain authoritative (R5).
    enforcement = failClosedState(incarnationId, "reconciliation-in-progress", brainHome, roleHint);

    try {
      let load: LoadOutcome;
      activeGoalPolicy = undefined;
      if (v4Load) {
        load = v4Load;
        roleHint = v4Load.manifest.role;
      } else {
        if (profileRole === null) {
          const stage = env.MOSAIC_AGENT_NAME ? "no-seat-profile" : "no-agent-name";
          load = { ok: false, failure: { stage } as LoadOutcome extends { ok: false; failure: infer F } ? F : never };
        } else {
          load = loadTrustedManifest(brainHome, profileRole, io, { incarnationId, launchGeneration: configuredLaunchGeneration });
          if (load.ok) roleHint = load.manifest.role;
        }
        if (load.ok && load.manifest.schemaVersion === 4) v4Load = load;
      }
      if (load.ok && load.manifest.schemaVersion === 4) {
        const policy = load.goalPolicy?.attestation;
        if (!policy) {
          load = { ok: false, failure: { stage: "goal-policy-publication" } };
        } else if (!v4Published) {
          const publication = publishGoalPolicy(policy, (reason) => {
            try {
              journal.append({ kind: "denial", tool: "goal_report", reason: `mosaic-core:goal-policy-denied:${reason}` });
            } catch {
              console.warn("[mosaic-core] journal append failed (enforcement unaffected; details suppressed)");
            }
          });
          if (!publication.ok) {
            load = { ok: false, failure: { stage: "goal-policy-publication" } };
          } else {
            v4Published = true;
            activeGoalPolicy = publication.attestation;
          }
        } else {
          activeGoalPolicy = policy;
        }
      }
      const application = buildApplication({
        load,
        activeTools: pi.getActiveTools(),
        incarnationId,
        roleHint,
        brainHome,
      });
      pi.setActiveTools(application.applyTools);
      const got = [...pi.getActiveTools()].sort();
      const want = [...application.applyTools].sort();
      if (JSON.stringify(got) !== JSON.stringify(want)) {
        enforcement = failClosedState(incarnationId, "postcondition-failed", brainHome, roleHint);
        // A mismatch is not merely a status value. Remove the broad/incorrect
        // active projection before returning; interception remains the final
        // denial if the platform rejects this recovery call too.
        try { pi.setActiveTools([...enforcement.allowed].sort()); } catch { /* interception governs */ }
        try { journal.append({ kind: "reconciliation", state: "fail-closed", cause: "postcondition-failed", removed: [], added: [] }); } catch (e) { console.warn("[mosaic-core] journal append failed (enforcement unaffected; details suppressed)"); }
        return;
      }
      enforcement = application.state;
      try {
        journal.append({
          kind: "reconciliation",
          state: application.state.state,
          role: application.state.state === "applied" ? application.state.role : undefined,
          revision: application.state.state === "applied" ? application.state.revision : undefined,
          digest: application.state.state === "applied" ? application.state.digest : undefined,
          cause: application.state.state === "fail-closed" ? application.state.cause : undefined,
          removed: application.plan ? application.plan.toRemove : [],
          added: application.plan ? application.plan.toAdd : [],
        });
      } catch (e) { console.warn("[mosaic-core] journal append failed (enforcement unaffected; details suppressed)"); }
    } catch (reconErr) {
      // Platform call threw mid-reconciliation: the provisional fail-closed
      // state GOVERNS — the old applied policy is dead.
      // NG4-CAUSE: STABLE cause only — never embed the raw exception.
      // status EXPOSES cause; an injected/platform error could carry
      // sensitive content into model-visible denial reasons.
      enforcement = failClosedState(incarnationId, "reconciliation-threw", brainHome, roleHint);
      try { pi.setActiveTools([...enforcement.allowed].sort()); } catch { /* best-effort; interception governs */ }
      try { journal.append({ kind: "reconciliation", state: "fail-closed", cause: "reconciliation-threw", removed: [], added: [] }); } catch { /* evidence never bypasses enforcement */ }
    }
  });

  pi.on("tool_call", async (event: PiToolCallEvent) => {
    // F7-(1): wire event.input through so the read-containment check sees
    // the path argument. F7-B precision: for read-family tools (read,
    // grep, find, ls) with an ABSENT path, Pi executes against the tool's
    // own cwd — an uncontrolled location. We MUTATE the input to pin the
    // path to the trusted brain home (Pi guarantees mutation affects
    // execution and is not revalidated). The test suite asserts the
    // executed input IS pinned, not just the decision result.
    // F7E: read.path is REQUIRED in Pi — absent/malformed input is DENIED
    // by the enforcement layer (no synthesis, no cwd ambiguity). Only ls
    // gets absent-path pinning (it lists a directory, not a file, and its
    // path is genuinely optional in Pi).
    if ((SAFE_READ_TOOLS as readonly string[]).includes(event.toolName)) {
      // (2) ls with UNDEFINED input: assign {path: brainHome} (safe dir listing)
      // FIX2-(1): synthesize ONLY when event.input is EXACTLY undefined.
      // null / 42 / [] are malformed and must reach stable DENIAL, not be
      // silently mutated into a valid input.
      if (event.toolName === "ls" && event.input === undefined) {
        event.input = { path: brainHome };
      }
      if (event.input && typeof event.input === "object") {
        const input = event.input as { path?: unknown };
        // ls with absent path in an existing object: pin to brainHome
        if (event.toolName === "ls" && (input.path === undefined || input.path === "")) {
          input.path = brainHome;
        }
        // (3) Resolve RELATIVE paths against brainHome BEFORE realpath
        if (typeof input.path === "string" && input.path !== "" && !input.path.startsWith("/")) {
          input.path = brainHome + "/" + input.path;
        }
        // F7C-(1): realpath existing targets — symlink escape resolution
        if (typeof input.path === "string" && input.path !== "") {
          try {
            input.path = realpathSync(input.path);
          } catch {
            // path doesn't exist yet — leave as-is; containment handles traversal
          }
        }
      }
    }
    if (event.toolName === "goal_report" && activeGoalPolicy) {
      const policy = verifyGoalPolicyPublication(activeGoalPolicy);
      if (!policy.ok) {
        const reason = `mosaic-core:goal-policy-denied:${policy.reason}`;
        try {
          journal.append({ kind: "denial", tool: event.toolName, reason });
        } catch {
          console.warn("[mosaic-core] journal append failed (enforcement unaffected; details suppressed)");
        }
        return { block: true, reason };
      }
    }
    const decision = decideToolCall(enforcement, event.toolName, event.input, brainHome);
    if (decision.block) {
      // PART B: evidence failure must NEVER bypass enforcement — the denial
      // returns even if the journal append throws (disk full, permission,
      // injected failure)
      try {
        journal.append({ kind: "denial", tool: event.toolName, reason: decision.reason });
      } catch (journalErr) {
        console.warn("[mosaic-core] journal append failed (enforcement unaffected; details suppressed)");
      }
      return { block: true, reason: decision.reason };
    }
    return undefined;
  });
  // [NG-2 enforcement binding end]
}