import { z } from 'zod';

import { parseBooleanEnv } from '#/_base/utils/env';
import {
  type EnvBindings,
  envBindings,
  stripEnvBoundFields,
  type IConfigService,
} from '#/app/config/config';
import { registerConfigSection } from '#/app/config/configSectionContributions';

export const TASK_SECTION = 'task';
export const LEGACY_BACKGROUND_SECTION = 'background';

export const PrintBackgroundModeSchema = z.enum(['exit', 'drain', 'steer']);

export type PrintBackgroundMode = z.infer<typeof PrintBackgroundModeSchema>;

export const AgentTaskConfigSchema = z.object({
  maxRunningTasks: z.number().int().min(1).optional(),
  keepAliveOnExit: z.boolean().optional(),
  bashAutoBackgroundOnTimeout: z.boolean().optional(),
  bashTaskTimeoutS: z.number().int().min(0).optional(),
  killGracePeriodMs: z.number().int().min(0).optional(),
  printWaitCeilingS: z.number().int().min(1).optional(),
  printBackgroundMode: PrintBackgroundModeSchema.optional(),
  printMaxTurns: z.number().int().min(1).optional(),
});

export type AgentTaskConfig = z.infer<typeof AgentTaskConfigSchema>;

export function resolveAgentTaskConfig(config: IConfigService): AgentTaskConfig | undefined {
  const legacy = config.get<AgentTaskConfig | undefined>(LEGACY_BACKGROUND_SECTION);
  const current = config.get<AgentTaskConfig | undefined>(TASK_SECTION);
  if (legacy === undefined) return current;
  if (current === undefined) return legacy;
  return { ...legacy, ...current };
}

export function resolvePrintBackgroundMode(config: IConfigService): PrintBackgroundMode {
  const section = resolveAgentTaskConfig(config);
  if (section?.printBackgroundMode !== undefined) return section.printBackgroundMode;
  return section?.keepAliveOnExit === true ? 'drain' : 'steer';
}

export const KEEP_ALIVE_ON_EXIT_ENV = 'KIMI_CODE_BACKGROUND_KEEP_ALIVE_ON_EXIT';
export const MAX_RUNNING_TASKS_ENV = 'KIMI_CODE_BACKGROUND_MAX_RUNNING_TASKS';
export const BASH_TASK_TIMEOUT_S_ENV = 'KIMI_CODE_BACKGROUND_BASH_TASK_TIMEOUT_S';
export const PRINT_WAIT_CEILING_S_ENV = 'KIMI_CODE_BACKGROUND_PRINT_WAIT_CEILING_S';
export const PRINT_BACKGROUND_MODE_ENV = 'KIMI_CODE_BACKGROUND_PRINT_BACKGROUND_MODE';
export const PRINT_MAX_TURNS_ENV = 'KIMI_CODE_BACKGROUND_PRINT_MAX_TURNS';

function parsePositiveInt(raw: string): number | undefined {
  const value = raw.trim();
  if (value.length === 0 || !/^\d+$/.test(value)) return undefined;
  const parsed = Number(value);
  return Number.isSafeInteger(parsed) && parsed > 0 ? parsed : undefined;
}

function parseNonNegativeInt(raw: string): number | undefined {
  const value = raw.trim();
  if (value.length === 0 || !/^\d+$/.test(value)) return undefined;
  const parsed = Number(value);
  return Number.isSafeInteger(parsed) && parsed >= 0 ? parsed : undefined;
}

function parsePrintBackgroundMode(raw: string): PrintBackgroundMode | undefined {
  const parsed = PrintBackgroundModeSchema.safeParse(raw.trim());
  return parsed.success ? parsed.data : undefined;
}

export const taskEnvBindings: EnvBindings<AgentTaskConfig> = envBindings(AgentTaskConfigSchema, {
  keepAliveOnExit: { env: KEEP_ALIVE_ON_EXIT_ENV, parse: parseBooleanEnv },
  maxRunningTasks: { env: MAX_RUNNING_TASKS_ENV, parse: parsePositiveInt },
  bashTaskTimeoutS: { env: BASH_TASK_TIMEOUT_S_ENV, parse: parseNonNegativeInt },
  printWaitCeilingS: { env: PRINT_WAIT_CEILING_S_ENV, parse: parsePositiveInt },
  printBackgroundMode: { env: PRINT_BACKGROUND_MODE_ENV, parse: parsePrintBackgroundMode },
  printMaxTurns: { env: PRINT_MAX_TURNS_ENV, parse: parsePositiveInt },
});

export const stripTaskEnv = stripEnvBoundFields(taskEnvBindings);

registerConfigSection(TASK_SECTION, AgentTaskConfigSchema, {
  env: taskEnvBindings,
  stripEnv: stripTaskEnv,
});
registerConfigSection(LEGACY_BACKGROUND_SECTION, AgentTaskConfigSchema, {
  env: taskEnvBindings,
  stripEnv: stripTaskEnv,
});