import {
  DEBUGGER_CONTROL_REPLY_BYTES,
  DEFAULT_DEBUGGER_COMMAND_DEADLINE_MS,
  DEFAULT_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
  DEFAULT_DEBUGGER_MAX_PENDING_COMMANDS,
  DEFAULT_DEBUGGER_MAX_SESSIONS,
  MAXIMUM_DEBUGGER_COMMAND_DEADLINE_MS,
  MAXIMUM_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
  MAXIMUM_DEBUGGER_MAX_PENDING_COMMANDS,
  MAXIMUM_DEBUGGER_MAX_SESSIONS,
  MINIMUM_DEBUGGER_COMMAND_DEADLINE_MS,
  MINIMUM_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
  MINIMUM_DEBUGGER_MAX_PENDING_COMMANDS,
  MINIMUM_DEBUGGER_MAX_SESSIONS,
} from "../domain/analysisResourceLimits.js";
import { ConfigurationError } from "../domain/configurationErrors.js";
import { err, ok, type Result } from "../domain/result.js";
import { positiveDecimalIntegerSchema } from "./positiveDecimalInteger.js";

/**
 * Launch caps shared by GDB and Rizin. Each setting is declared here once.
 * Startup validation spreads {@link debuggerSessionLimitEnvironmentShape};
 * it does not restate the name, bounds, or schema.
 */
export const DEBUGGER_COMMAND_DEADLINE_SETTING =
  "REA_DEBUGGER_COMMAND_DEADLINE_MS";
export const DEBUGGER_MAX_SESSIONS_SETTING = "REA_DEBUGGER_MAX_SESSIONS";
export const DEBUGGER_MAX_PENDING_COMMANDS_SETTING =
  "REA_DEBUGGER_MAX_PENDING_COMMANDS";
export const DEBUGGER_MAX_COMMAND_OUTPUT_BYTES_SETTING =
  "REA_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES";

/** Effective debugger admission and where its value came from. */
export interface DebuggerAdmissionLimit {
  readonly setting: string;
  readonly value: number;
  readonly source: "default" | "setting" | "runtime";
  readonly defaultValue: number;
  readonly minimum: number;
  readonly maximum: number;
  readonly unit: "ms" | "bytes" | "sessions" | "commands";
}

const limit = (
  setting: string,
  value: number,
  minimum: number,
  maximum: number,
  unit: DebuggerAdmissionLimit["unit"],
): DebuggerAdmissionLimit => ({
  setting,
  value,
  source: "default",
  defaultValue: value,
  minimum,
  maximum,
  unit,
});

export const DEFAULT_DEBUGGER_COMMAND_DEADLINE: DebuggerAdmissionLimit = limit(
  DEBUGGER_COMMAND_DEADLINE_SETTING,
  DEFAULT_DEBUGGER_COMMAND_DEADLINE_MS,
  MINIMUM_DEBUGGER_COMMAND_DEADLINE_MS,
  MAXIMUM_DEBUGGER_COMMAND_DEADLINE_MS,
  "ms",
);
export const DEFAULT_DEBUGGER_MAX_SESSIONS_LIMIT: DebuggerAdmissionLimit =
  limit(
    DEBUGGER_MAX_SESSIONS_SETTING,
    DEFAULT_DEBUGGER_MAX_SESSIONS,
    MINIMUM_DEBUGGER_MAX_SESSIONS,
    MAXIMUM_DEBUGGER_MAX_SESSIONS,
    "sessions",
  );
export const DEFAULT_DEBUGGER_MAX_PENDING_COMMANDS_LIMIT: DebuggerAdmissionLimit =
  limit(
    DEBUGGER_MAX_PENDING_COMMANDS_SETTING,
    DEFAULT_DEBUGGER_MAX_PENDING_COMMANDS,
    MINIMUM_DEBUGGER_MAX_PENDING_COMMANDS,
    MAXIMUM_DEBUGGER_MAX_PENDING_COMMANDS,
    "commands",
  );
export const DEFAULT_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES_LIMIT: DebuggerAdmissionLimit =
  limit(
    DEBUGGER_MAX_COMMAND_OUTPUT_BYTES_SETTING,
    DEFAULT_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
    MINIMUM_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
    MAXIMUM_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
    "bytes",
  );

const constraintFor = (admission: DebuggerAdmissionLimit): string =>
  `${admission.setting} must be a positive decimal integer from ${String(admission.minimum)} to ${String(admission.maximum)} ${admission.unit}; the default is ${String(admission.defaultValue)} ${admission.unit}.${
    admission.unit === "ms"
      ? " Node schedules a delay above that maximum as 1 ms, so a larger value is refused."
      : ""
  }`;

export const debuggerCommandDeadlineConstraint = constraintFor(
  DEFAULT_DEBUGGER_COMMAND_DEADLINE,
);
export const debuggerMaxSessionsConstraint = constraintFor(
  DEFAULT_DEBUGGER_MAX_SESSIONS_LIMIT,
);
export const debuggerMaxPendingCommandsConstraint = constraintFor(
  DEFAULT_DEBUGGER_MAX_PENDING_COMMANDS_LIMIT,
);
export const debuggerMaxCommandOutputBytesConstraint = constraintFor(
  DEFAULT_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES_LIMIT,
);

export const debuggerCommandDeadlineMsSchema = positiveDecimalIntegerSchema(
  MINIMUM_DEBUGGER_COMMAND_DEADLINE_MS,
  MAXIMUM_DEBUGGER_COMMAND_DEADLINE_MS,
  debuggerCommandDeadlineConstraint,
);
export const debuggerMaxSessionsSchema = positiveDecimalIntegerSchema(
  MINIMUM_DEBUGGER_MAX_SESSIONS,
  MAXIMUM_DEBUGGER_MAX_SESSIONS,
  debuggerMaxSessionsConstraint,
);
export const debuggerMaxPendingCommandsSchema = positiveDecimalIntegerSchema(
  MINIMUM_DEBUGGER_MAX_PENDING_COMMANDS,
  MAXIMUM_DEBUGGER_MAX_PENDING_COMMANDS,
  debuggerMaxPendingCommandsConstraint,
);
export const debuggerMaxCommandOutputBytesSchema = positiveDecimalIntegerSchema(
  MINIMUM_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
  MAXIMUM_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES,
  debuggerMaxCommandOutputBytesConstraint,
);

/** Schemas startup validation spreads. The setting names are not restated. */
export const debuggerSessionLimitEnvironmentShape = {
  [DEBUGGER_COMMAND_DEADLINE_SETTING]:
    debuggerCommandDeadlineMsSchema.optional(),
  [DEBUGGER_MAX_SESSIONS_SETTING]: debuggerMaxSessionsSchema.optional(),
  [DEBUGGER_MAX_PENDING_COMMANDS_SETTING]:
    debuggerMaxPendingCommandsSchema.optional(),
  [DEBUGGER_MAX_COMMAND_OUTPUT_BYTES_SETTING]:
    debuggerMaxCommandOutputBytesSchema.optional(),
};

export interface DebuggerSessionLimits {
  readonly commandDeadline: DebuggerAdmissionLimit;
  readonly maxSessions: DebuggerAdmissionLimit;
  readonly maxPendingCommands: DebuggerAdmissionLimit;
  readonly maxCommandOutputBytes: DebuggerAdmissionLimit;
}

const parseOne = (
  admission: DebuggerAdmissionLimit,
  schema: ReturnType<typeof positiveDecimalIntegerSchema>,
  constraint: string,
  value: string | undefined,
): Result<DebuggerAdmissionLimit, ConfigurationError> => {
  if (value === undefined) return ok(admission);
  const parsed = schema.safeParse(value);
  return parsed.success
    ? ok({ ...admission, value: parsed.data, source: "setting" })
    : err(
        new ConfigurationError(constraint, {
          settings: [{ setting: admission.setting, constraint }],
        }),
      );
};

/** Resolve every shared debugger cap from one environment. Invalid values are refused. */
export const parseDebuggerSessionLimits = (
  environment: Readonly<Record<string, string | undefined>>,
): Result<DebuggerSessionLimits, ConfigurationError> => {
  const commandDeadline = parseOne(
    DEFAULT_DEBUGGER_COMMAND_DEADLINE,
    debuggerCommandDeadlineMsSchema,
    debuggerCommandDeadlineConstraint,
    environment[DEBUGGER_COMMAND_DEADLINE_SETTING],
  );
  const maxSessions = parseOne(
    DEFAULT_DEBUGGER_MAX_SESSIONS_LIMIT,
    debuggerMaxSessionsSchema,
    debuggerMaxSessionsConstraint,
    environment[DEBUGGER_MAX_SESSIONS_SETTING],
  );
  const maxPendingCommands = parseOne(
    DEFAULT_DEBUGGER_MAX_PENDING_COMMANDS_LIMIT,
    debuggerMaxPendingCommandsSchema,
    debuggerMaxPendingCommandsConstraint,
    environment[DEBUGGER_MAX_PENDING_COMMANDS_SETTING],
  );
  const maxCommandOutputBytes = parseOne(
    DEFAULT_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES_LIMIT,
    debuggerMaxCommandOutputBytesSchema,
    debuggerMaxCommandOutputBytesConstraint,
    environment[DEBUGGER_MAX_COMMAND_OUTPUT_BYTES_SETTING],
  );
  const settings = [
    commandDeadline,
    maxSessions,
    maxPendingCommands,
    maxCommandOutputBytes,
  ].flatMap((result) => (result.ok ? [] : result.error.settings));
  if (
    settings.length > 0 ||
    !commandDeadline.ok ||
    !maxSessions.ok ||
    !maxPendingCommands.ok ||
    !maxCommandOutputBytes.ok
  )
    return err(
      new ConfigurationError("Invalid REA environment configuration", {
        settings,
      }),
    );
  return ok({
    commandDeadline: commandDeadline.value,
    maxSessions: maxSessions.value,
    maxPendingCommands: maxPendingCommands.value,
    maxCommandOutputBytes: maxCommandOutputBytes.value,
  });
};

/** Refuse an invalid launch cap instead of falling back to the default. */
export const resolveDebuggerSessionLimits = (
  environment: Readonly<Record<string, string | undefined>>,
): DebuggerSessionLimits => {
  const parsed = parseDebuggerSessionLimits(environment);
  if (!parsed.ok) throw parsed.error;
  return parsed.value;
};

/**
 * Fixed budget for Rizin cleanup readback and GDB startup or detach MI.
 * This is not `REA_DEBUGGER_MAX_COMMAND_OUTPUT_BYTES`. A caller cap below
 * this budget must not truncate those required replies, and recovery for
 * this budget is not an environment setting.
 */
export const debuggerControlReplyOutput: DebuggerAdmissionLimit = {
  setting: "debugger control-reply budget",
  value: DEBUGGER_CONTROL_REPLY_BYTES,
  source: "default",
  defaultValue: DEBUGGER_CONTROL_REPLY_BYTES,
  minimum: DEBUGGER_CONTROL_REPLY_BYTES,
  maximum: DEBUGGER_CONTROL_REPLY_BYTES,
  unit: "bytes",
};

/** Test and caller seams replace the launch value and record that source. */
export const applyDebuggerAdmissionOverride = (
  admission: DebuggerAdmissionLimit,
  value: number | undefined,
): DebuggerAdmissionLimit =>
  value === undefined ? admission : { ...admission, value, source: "runtime" };