import { RegularFileCleanupFailure } from "../filesystem/OwnedRegularFile.js";
import { readClientPolicyBlock } from "./GeminiClientSettings.js";
import { readEffectiveClientRegistrationConfiguration } from "./ClientConfigurationFiles.js";
import {
  clientServerForcedEnabled,
  clientServerListedDisabled,
  effectiveClientServer,
  type ClientConfigurationDocument,
} from "./ClientConfigurationDocument.js";
import { lstat, stat } from "node:fs/promises";
import { err, ok, type Result } from "../domain/result.js";

import { PRODUCT_IDENTITY } from "../identity.js";
import { snapshotEnvironment } from "../process/snapshotEnvironment.js";
import { CURRENT_ENTRYPOINT_PATH } from "../process/CurrentEntrypointPath.js";
import {
  MCP_STARTUP_POLICY,
  mcpProviderDeadlineAllowanceMs,
  recommendedMcpToolTimeoutMs,
  recommendedMcpToolTimeoutSeconds,
  type McpToolTimeoutInputs,
} from "../mcpStartupPolicy.js";
import {
  inspectClientRegistrationCommand,
  type ClientRegistrationCommandFacts,
  type ClientRegistrationCommandIdentity,
} from "./ClientRegistrationIdentity.js";
import {
  clientEvidencePaths,
  clientOwnershipEvidencePaths,
  compactInputSchemaByDefault,
  manualRegistrationRemediation,
  supportedClients,
} from "./SupportedClients.js";
import type { SetupClient } from "./SupportedClients.js";
import { compareUnicodeCodePoints } from "../domain/unicodeCodePointOrder.js";
import { dshDocument } from "./DshCordisPatch.js";
import {
  clientRegistrationEnvironmentDetailsWithBudget,
  recordedProviderSettings,
} from "./ClientRegistrationEnvironment.js";
import type {
  OwnedProviderSetting,
  ProviderRequestBudgetResolver,
  RecordedProviderSettings,
} from "./ClientRegistrationEnvironment.js";
import type { ArtifactResourceScope } from "../artifacts/ArtifactResourceScope.js";

import {
  parseClientRegistrationPolicy,
  parseClientRegistrationLauncher,
  clientRegistrationOwnershipRemediation,
  setupPreservesDisabledActivation,
  type ClientRegistration,
} from "./ClientRegistration.js";
import { admitClientStdioConnection } from "./ClientRegistrationConnection.js";

interface ClientRegistrationStatusBase {
  readonly client: string;
  readonly config_path: string;
  /** Parsed launcher ownership; independent of readiness and retained without reinspection. */
  readonly command_identity: ClientRegistrationCommandIdentity;
  /** Exact package reference requested by npx/bunx, when registration uses one. */
  readonly package_reference?: string;
  /** Non-blocking timeout guidance; caller-selected values remain aligned. */
  readonly advisory?: string;
  /** Provider settings this process selected that the registration's file does not carry. */
  readonly provider_settings?: RecordedProviderSettings;
}

type RegistrationCommand = readonly [string, ...string[]];

export type ClientRegistrationStatus = ClientRegistrationStatusBase &
  (
    | {
        readonly command: RegistrationCommand;
        readonly state: "aligned";
        readonly remediation: null;
      }
    | {
        readonly command: RegistrationCommand;
        readonly state: "stale";
        readonly remediation: string;
      }
    | {
        readonly command: RegistrationCommand;
        readonly state: "unknown";
        readonly remediation: string;
      }
    | {
        readonly command: readonly [];
        readonly state: "missing" | "invalid" | "manual";
        readonly remediation: string;
      }
  );

export type UnhealthyClientRegistrationStatus = Exclude<
  ClientRegistrationStatus,
  { readonly state: "aligned" }
>;

interface ClientRegistrationReadOptions {
  readonly platform?: NodeJS.Platform;
  readonly environment?: NodeJS.ProcessEnv;
  readonly resources?: ArtifactResourceScope;
  readonly selectedClientIds?: readonly string[];
  /**
   * Which evidence authorises inspection. `readiness` inspects a client whose
   * product applicability is established, plus clients the caller selected
   * explicitly. `ownership` also inspects shared registration storage, because
   * a version-pinned registration REA wrote must be refreshed even when the
   * product profile is absent.
   */
  readonly evidence?: "readiness" | "ownership";
  readonly resolveProviderRequestBudget?: ProviderRequestBudgetResolver;
  /** Settings to compare with each registration's file; omitted skips that read. */
  readonly providerSettings?: Readonly<Record<string, string>>;
  /** Which recorded provider settings hold a value the caller owns. */
  readonly ownedProviderSetting?: OwnedProviderSetting;
  /** Inspect selected resolved settings without returning their values in status. */
  readonly observeProviderSetting?: (
    client: string,
    name: string,
    value: string,
  ) => void;
}

/** Registration facts shared by diagnostics and update maintenance. */
export interface ClientRegistrationInspection {
  readonly status: ClientRegistrationStatus;
  readonly activation: "enabled" | "disabled" | "unknown";
}

/** Project diagnostics from the same inspection used to select maintenance. */
export const readClientRegistrationStatuses = async (
  home: string,
  currentCommandPath: string | undefined = CURRENT_ENTRYPOINT_PATH,
  options: ClientRegistrationReadOptions = {},
): Promise<readonly ClientRegistrationStatus[]> =>
  (
    await readClientRegistrationInspections(home, currentCommandPath, options)
  ).map(({ status }) => status);

/** Parse effective registrations and their client-specific activation once.
 * A supplied scope retains failed cleanup; otherwise transfer its exact failure.
 */
export const readClientRegistrationInspections = async (
  home: string,
  currentCommandPath: string | undefined = CURRENT_ENTRYPOINT_PATH,
  options: ClientRegistrationReadOptions = {},
): Promise<readonly ClientRegistrationInspection[]> => {
  const inspections: ClientRegistrationInspection[] = [];
  const record = (
    status: ClientRegistrationStatus,
    activation: ClientRegistrationInspection["activation"] = "unknown",
  ): void => {
    inspections.push({ status, activation });
  };
  for (const client of supportedClients(
    home,
    options.platform,
    options.environment,
  )) {
    const selected = options.selectedClientIds?.includes(client.name) === true;
    if (client.configPathError !== undefined) {
      record({
        client: client.name,
        config_path: client.configPath,
        command: [],
        command_identity: "unknown",
        state: "invalid",
        remediation: client.configPathError,
      });
      continue;
    }
    const presence = await clientEvidencePresent(client, {
      selected,
      ownership: options.evidence === "ownership",
    });
    if (!presence.ok) {
      record({
        client: client.name,
        config_path: presence.error.path,
        command: [],
        command_identity: "unknown",
        state: "invalid",
        remediation: presence.error.detail,
      });
      continue;
    }
    if (!presence.value) continue;
    const manualRemediation = manualRegistrationRemediation(client.name);
    if (client.format === "unsupported") {
      if (manualRemediation !== undefined)
        record({
          client: client.name,
          config_path: client.markerPath ?? client.configPath,
          command: [],
          command_identity: "unknown",
          state: "manual",
          remediation: manualRemediation,
        });
      continue;
    }
    let selectedConfigPath = client.configPath;
    try {
      const configuration = await readEffectiveClientRegistrationConfiguration(
        client,
        options.resources,
        options.platform,
      );
      if (!configuration.ok) {
        if (
          options.resources === undefined &&
          configuration.error.cleanupFailure !== undefined
        )
          throw configuration.error.cleanupFailure;
        record({
          client: client.name,
          config_path: configuration.error.path,
          command: [],
          command_identity: "unknown",
          state: "invalid",
          remediation: configuration.error.detail,
        });
        continue;
      }
      const { document: parsed, configPath } = configuration.value;
      selectedConfigPath = configPath;
      if (parsed === undefined) {
        record(unavailableStatus(client, "missing", configPath));
        continue;
      }
      const policy = await readClientPolicyBlock(
        client,
        parsed,
        undefined,
        options.resources,
      );
      if (!policy.ok) {
        if (
          options.resources === undefined &&
          policy.error.cleanupFailure !== undefined
        )
          throw policy.error.cleanupFailure;
        record({
          client: client.name,
          config_path: configPath,
          command: [],
          command_identity: "unknown",
          state: "invalid",
          remediation: policy.error.detail,
        });
        continue;
      }
      const policyBlock = policy.value;
      const raw = effectiveClientServer(parsed, PRODUCT_IDENTITY.mcpServerKey);
      if (raw === undefined) {
        const editabilityError =
          parsed.dialect === "dsh"
            ? dshDocument(parsed.document).editabilityError
            : undefined;
        if (editabilityError !== undefined) {
          record({
            client: client.name,
            config_path: configPath,
            command: [],
            command_identity: "unknown",
            state: "invalid",
            remediation: editabilityError.message,
          });
          continue;
        }
        record(unavailableStatus(client, "missing", configPath));
        continue;
      }
      const effectiveClient: SetupClient =
        parsed.dialect === "zcode_fallback"
          ? {
              ...client,
              configPath,
              configPaths: [configPath],
              format: "zcode_fallback",
            }
          : client;
      const parsedRegistration = parseClientRegistrationPolicy(
        raw,
        effectiveClient,
      );
      if (!parsedRegistration.ok) {
        // Invalid readiness settings do not erase a usable launcher identity.
        const launcher = parseClientRegistrationLauncher(raw, {
          dialect: parsed.dialect,
          profile: client.registrationProfile,
        });
        const commandIdentity = launcher.ok
          ? inspectClientRegistrationCommand(
              [launcher.value.command, ...launcher.value.args],
              currentCommandPath,
            ).identity
          : "unknown";
        record({
          client: client.name,
          config_path: configPath,
          command: [],
          command_identity: commandIdentity,
          state: "invalid",
          remediation: `${parsedRegistration.error.message}: ${parsedRegistration.error.settings.map(({ setting, constraint }) => `${setting}: ${constraint}`).join("; ")}`,
        });
        continue;
      }
      const registration = parsedRegistration.value;
      const command: RegistrationCommand = [
        registration.command,
        ...registration.args,
      ];
      const commandFacts = inspectClientRegistrationCommand(
        command,
        currentCommandPath,
      );
      const nativeApplicability = admitClientStdioConnection(raw, {
        dialect: parsed.dialect,
        profile: client.registrationProfile,
      });
      if (
        !nativeApplicability.ok &&
        nativeApplicability.error.kind === "invalid"
      ) {
        record({
          client: client.name,
          config_path: configPath,
          command: [],
          command_identity: commandFacts.identity,
          state: "invalid",
          remediation: nativeApplicability.error.cause.message,
        });
        continue;
      }
      const registrationEnvironment =
        compactInputSchemaByDefault(client) || client.name === "codex"
          ? await clientRegistrationEnvironmentDetailsWithBudget(
              parsed,
              client,
              {},
              "effective",
              client.name === "kimi" || client.name === "codex"
                ? options.resolveProviderRequestBudget
                : undefined,
              options.platform,
            )
          : undefined;
      if (
        registrationEnvironment !== undefined &&
        !registrationEnvironment.ok
      ) {
        record({
          client: client.name,
          config_path: configPath,
          command: [],
          command_identity: commandFacts.identity,
          state: "invalid",
          remediation: registrationEnvironment.error.message,
        });
        continue;
      }
      const packageReference = commandFacts.package?.reference;
      const activation = registrationActivation(registration, client, parsed);
      const packageVersion = commandFacts.package?.exactVersion;
      const packageVersionDrift =
        packageVersion !== undefined &&
        packageVersion !== PRODUCT_IDENTITY.packageVersion;
      const alignment = !nativeApplicability.ok
        ? "unknown"
        : registrationAligned({
            registration,
            client: effectiveClient,
            commandFacts,
            inputSchemaProfileSelected:
              registrationEnvironment?.ok === true &&
              snapshotEnvironment(
                registrationEnvironment.value.values,
                options.platform,
              ).REA_MCP_INPUT_SCHEMA_PROFILE !== undefined,
          });
      record(
        configuredStatus(
          effectiveClient,
          command,
          commandFacts.identity,
          alignment === "unknown"
            ? "unknown"
            : activation === "enabled" &&
                !packageVersionDrift &&
                alignment === "aligned" &&
                (parsed.dialect !== "dsh" ||
                  dshDocument(parsed.document).ready) &&
                policyBlock === undefined
              ? "aligned"
              : "stale",
          (parsed.dialect !== "dsh" && commandFacts.identity !== "owned"
            ? clientRegistrationOwnershipRemediation(commandFacts.identity, [
                configPath,
              ])
            : undefined) ??
            (!nativeApplicability.ok
              ? nativeApplicability.error.cause.message
              : undefined) ??
            policyBlock ??
            (packageVersionDrift
              ? packageVersionRemediation(packageReference ?? "", client)
              : alignment === "unknown"
                ? unknownEntryPointRemediation()
                : undefined) ??
            // Only a target whose setup preserves the flag is a manual
            // conflict; a native row (for example ZCode's own storage) is
            // still repaired by its setup run below.
            (activation === "disabled" &&
            registration.enable === false &&
            setupPreservesDisabledActivation(
              effectiveClient,
              effectiveClient.format,
            )
              ? sharedDisabledActivationRemediation()
              : undefined),
          packageReference,
          registrationEnvironment?.ok === true
            ? timeoutAdvisory(
                client,
                registration,
                registrationEnvironment.value.timeoutInputs,
              )
            : undefined,
          options.providerSettings === undefined
            ? undefined
            : recordedProviderSettings(
                parsed,
                client,
                options.providerSettings,
                options.platform,
                options.ownedProviderSetting,
                options.observeProviderSetting === undefined
                  ? undefined
                  : (name, value) =>
                      options.observeProviderSetting!(client.name, name, value),
              ),
        ),
        activation,
      );
    } catch (cause: unknown) {
      if (
        options.resources === undefined &&
        cause instanceof RegularFileCleanupFailure
      )
        throw cause;
      record(
        unavailableStatus(
          client,
          isMissing(cause) ? "missing" : "invalid",
          selectedConfigPath,
        ),
      );
    }
  }
  return inspections.sort((left, right) =>
    compareUnicodeCodePoints(left.status.client, right.status.client),
  );
};

/** Shared registration storage doubles as ZCode's fallback, so its
 * `enable: false` activation fact binds every reader of that storage.
 * Maintenance must not drop the flag by rewriting the row as another
 * product's registration and silently re-enabling it; whether a repair
 * actually preserves it is setupPreservesDisabledActivation. */
const sharedEnableFlagBinds = (
  registration: ClientRegistration,
  client: SetupClient,
  parsed: ClientConfigurationDocument,
): boolean =>
  (parsed.dialect === "zcode" ||
    parsed.dialect === "zcode_fallback" ||
    client.sharedRegistration === true) &&
  registration.enable === false;

/** A disable that setup preserves is a manual conflict: its remediation
 * must not point at an ineffective setup run. */
const sharedDisabledActivationRemediation = (): string =>
  "This shared registration row carries enable: false, which binds every reader of the shared storage, including ZCode's fallback view. REA preserves that flag, so rea setup will not change this row. Re-enable it with the product that disabled it, or remove enable: false manually, then rerun rea doctor.";
// Codex and Kimi Code load a server marked `disabled: true` and honor only
// `enabled`; Devin loads one marked `enabled: false` and honors only `disabled`.
const ignoresDisabledKey = new Set(["codex", "kimi"]);
const ignoresEnabledKey = new Set(["devin"]);

const registrationActivation = (
  registration: ClientRegistration,
  client: SetupClient,
  parsed: ClientConfigurationDocument,
): "enabled" | "disabled" =>
  (client.format !== "grok" &&
    !ignoresDisabledKey.has(client.name) &&
    registration.disabled === true) ||
  (registration.enabled === false &&
    !ignoresEnabledKey.has(client.name) &&
    !clientServerForcedEnabled(parsed, PRODUCT_IDENTITY.mcpServerKey)) ||
  sharedEnableFlagBinds(registration, client, parsed) ||
  clientServerListedDisabled(parsed, PRODUCT_IDENTITY.mcpServerKey)
    ? "disabled"
    : "enabled";

const registrationAligned = ({
  registration,
  client,
  commandFacts,
  inputSchemaProfileSelected,
}: {
  readonly registration: ClientRegistration;
  readonly client: SetupClient;
  readonly commandFacts: ClientRegistrationCommandFacts;
  readonly inputSchemaProfileSelected: boolean;
}): "aligned" | "stale" | "unknown" => {
  const { identity } = commandFacts;
  if (identity === "unknown") return "unknown";
  if (identity === "foreign") return "stale";
  if (
    client.name === "grok_build" &&
    registration.startup_timeout_sec === undefined
  )
    return "stale";
  if (
    client.name === "codex" &&
    (registration.startup_timeout_sec === undefined ||
      registration.tool_timeout_sec === undefined)
  )
    return "stale";
  if (
    client.name === "kimi" &&
    (registration.startupTimeoutMs === undefined ||
      registration.toolTimeoutMs === undefined)
  )
    return "stale";
  if (compactInputSchemaByDefault(client) && !inputSchemaProfileSelected)
    return "stale";
  // Native transport is admitted separately; the Harness route must name REA.
  if (client.format === "dsh" && registration.serverName !== "rea")
    return "stale";
  // Legacy package runners remain owned, but setup migrates them to the selected installation.
  if (commandFacts.package !== undefined) return "stale";
  // Owning the script does not establish how its shebang interpreter resolves
  // in the client. Setup migrates these launchers without losing ownership.
  return commandFacts.launch === "runtime_script" ? "aligned" : "stale";
};

/** A client that rewrites its file from memory must be quit before setup. */
const remediation = (client: SetupClient): string => {
  if (client.quitBeforeSetup !== true)
    return "Run rea setup to refresh this registration, then restart the client.";
  const name = client.displayName ?? client.name;
  return `Quit ${name} fully, run rea setup to refresh this registration, then start ${name} again. A running ${name} can rewrite its configuration from memory and drop the registration.`;
};

const unknownEntryPointRemediation = (): string =>
  "The existing registration was retained because its executable identity cannot be verified. Check the registered launcher path, symlink targets and access permissions. Run the installed REA CLI or a supported package runner, then rerun rea doctor; no registration was changed.";

const configuredStatus = (
  client: SetupClient,
  command: RegistrationCommand,
  commandIdentity: ClientRegistrationCommandIdentity,
  state: "aligned" | "stale" | "unknown",
  policyRemediation?: string,
  packageReference?: string,
  advisory?: string,
  providerSettings?: RecordedProviderSettings,
): ClientRegistrationStatus =>
  state === "aligned"
    ? {
        client: client.name,
        config_path: client.configPath,
        command,
        command_identity: commandIdentity,
        ...(packageReference === undefined
          ? {}
          : { package_reference: packageReference }),
        state,
        remediation: null,
        ...(advisory === undefined ? {} : { advisory }),
        ...(providerSettings === undefined
          ? {}
          : { provider_settings: providerSettings }),
      }
    : {
        client: client.name,
        config_path: client.configPath,
        command,
        command_identity: commandIdentity,
        ...(packageReference === undefined
          ? {}
          : { package_reference: packageReference }),
        state,
        remediation: policyRemediation ?? remediation(client),
        ...(providerSettings === undefined
          ? {}
          : { provider_settings: providerSettings }),
      };

const timeoutAdvisory = (
  client: SetupClient,
  registration: ClientRegistration,
  timeoutInputs: McpToolTimeoutInputs,
): string | undefined => {
  const toolTimeout =
    client.name === "kimi"
      ? registration.toolTimeoutMs
      : client.name === "codex"
        ? registration.tool_timeout_sec
        : undefined;
  if (toolTimeout === undefined) return undefined;
  const providerAllowance = mcpProviderDeadlineAllowanceMs(timeoutInputs);
  const isKimi = client.name === "kimi";
  // A bigint is beyond the safe Number range, so rounding cannot cross the allowance.
  const toolTimeoutMs = Number(toolTimeout) * (isKimi ? 1 : 1000);
  const batchScope =
    timeoutInputs.ghidraDecompileTimeoutMs !== undefined &&
    (timeoutInputs.analysisProvider === "ghidra" ||
      timeoutInputs.analysisProvider === "auto")
      ? "The derived Ghidra deadline is a single-decompile estimate. For multi-function workflows such as batch_decompile, decompile_all or trace_native_values, allow startup plus every attempted function's limit and other work; split calls, reduce trace_native_values max_functions, or select a larger client deadline when needed. Explicit caller deadlines remain unchanged."
      : undefined;
  if (toolTimeoutMs >= providerAllowance) return batchScope;
  const setting = isKimi ? "toolTimeoutMs" : "tool_timeout_sec";
  const currentValue = isKimi
    ? `${String(toolTimeout)} ms`
    : `${String(toolTimeout)} seconds`;
  const recommendedValue = isKimi
    ? `${String(recommendedMcpToolTimeoutMs(timeoutInputs))} ms`
    : `${String(recommendedMcpToolTimeoutSeconds(timeoutInputs))} seconds`;
  const headroom = isKimi
    ? `${String(MCP_STARTUP_POLICY.toolOperationHeadroomMs)} ms`
    : `${String(MCP_STARTUP_POLICY.toolOperationHeadroomMs / 1000)} seconds`;
  const recommendation = `The configured ${setting} (${currentValue}) is shorter than REA's known provider allowance (${String(providerAllowance)} ms), so provider startup or an upstream request may exceed this client deadline. REA recommends ${setting} = ${recommendedValue} to cover that allowance plus ${headroom} of operation headroom; this additional headroom is a recommendation, not a guarantee for every analysis.`;
  return batchScope === undefined
    ? recommendation
    : `${recommendation} ${batchScope}`;
};

const packageVersionRemediation = (
  packageReference: string,
  client: SetupClient,
): string =>
  `This registration requests ${packageReference}, while the current REA CLI package is ${PRODUCT_IDENTITY.packageVersion}. REA does not resolve package-runner requests during doctor; update the registration with rea setup --client ${client.name}, then restart the client.`;

const unavailableStatus = (
  client: SetupClient,
  state: "missing" | "invalid",
  configPath: string,
): ClientRegistrationStatus => ({
  client: client.name,
  config_path: configPath,
  command: [],
  command_identity: "unknown",
  state,
  remediation: remediation(client),
});

/** Product discovery follows targets; configuration evidence retains entry presence. */
const clientEvidencePresent = async (
  client: SetupClient,
  evidence: { readonly selected: boolean; readonly ownership: boolean },
): Promise<
  Result<boolean, { readonly path: string; readonly detail: string }>
> => {
  // An explicit selection authorises the read outright: the caller named this
  // client, so an unreadable config must surface as unreadable instead of
  // collapsing to absence. The probes below serve automatic discovery only.
  if (evidence.selected) return ok(true);
  const discoveryPaths = new Set(client.discoveryPaths ?? []);
  const paths = [
    ...clientEvidencePaths(client),
    ...(evidence.ownership ? clientOwnershipEvidencePaths(client) : []),
  ];
  let unavailable:
    | { readonly path: string; readonly detail: string }
    | undefined;
  for (const path of paths) {
    try {
      await (discoveryPaths.has(path) ? stat(path) : lstat(path));
      return ok(true);
    } catch (cause: unknown) {
      if (!isMissing(cause))
        unavailable ??= {
          path,
          detail: `Client configuration evidence at ${path} could not be inspected: ${cause instanceof Error ? cause.message : String(cause)}. Check file permissions and rerun rea doctor.`,
        };
    }
  }
  return unavailable === undefined ? ok(false) : err(unavailable);
};

const isMissing = (cause: unknown): boolean =>
  cause instanceof Error && "code" in cause && cause.code === "ENOENT";