const DEFAULT_BIND_HOST = '127.0.0.1';
const DEFAULT_DATABASE_URL = 'file:data/fiscal.sqlite';
const DEFAULT_PORT = '3000';
const DEFAULT_PUBLIC_HOST = 'localhost';
const DEFAULT_SEC_USER_AGENT = 'Fiscal Clone <support@fiscal.local>';
const DEFAULT_WORKFLOW_LOCAL_DATA_DIR = '.workflow-data';
const DEFAULT_WORKFLOW_LOCAL_QUEUE_CONCURRENCY = '100';
const PLACEHOLDER_SECRET = 'replace-with-a-long-random-secret';

export const LOCAL_DEV_SECRET = 'fiscal-local-dev-secret-fiscal-local-dev-secret';

type EnvMap = Record<string, string | undefined>;

type LocalDevOverrideSummary = {
  apiBaseChanged: boolean;
  authOriginChanged: boolean;
  databaseChanged: boolean;
  secretFallbackUsed: boolean;
  workflowChanged: boolean;
};

export type LocalDevConfig = {
  bindHost: string;
  env: EnvMap;
  overrides: LocalDevOverrideSummary;
  port: string;
  publicOrigin: string;
};

function trim(value: string | undefined) {
  const candidate = value?.trim();
  return candidate ? candidate : undefined;
}

function parseCsvList(value: string | undefined) {
  return (value ?? '')
    .split(',')
    .map((entry) => entry.trim())
    .filter((entry) => entry.length > 0);
}

function toUniqueList(values: string[]) {
  return Array.from(new Set(values));
}

function coercePort(port: string | undefined) {
  const parsed = Number.parseInt(port ?? '', 10);
  if (Number.isInteger(parsed) && parsed > 0 && parsed <= 65535) {
    return String(parsed);
  }

  return DEFAULT_PORT;
}

function normalizeOrigin(origin: string) {
  const url = new URL(origin);

  if (url.protocol !== 'http:' && url.protocol !== 'https:') {
    throw new Error(`DEV_PUBLIC_ORIGIN must use http or https. Received: ${origin}`);
  }

  url.hash = '';
  url.search = '';

  const pathName = url.pathname.replace(/\/$/, '');
  return `${url.origin}${pathName === '/' ? '' : pathName}`;
}

function buildPublicOrigin(sourceEnv: EnvMap, port: string) {
  const explicitOrigin = trim(sourceEnv.DEV_PUBLIC_ORIGIN);
  if (explicitOrigin) {
    return normalizeOrigin(explicitOrigin);
  }

  const publicHost = trim(sourceEnv.DEV_PUBLIC_HOST) || DEFAULT_PUBLIC_HOST;
  return normalizeOrigin(`http://${publicHost}:${port}`);
}

function isSqliteLikeDatabase(databaseUrl: string) {
  return databaseUrl === ':memory:' || databaseUrl.startsWith('file:') || !databaseUrl.includes('://');
}

export function resolveSqlitePath(databaseUrl: string) {
  let databasePath = databaseUrl.startsWith('file:')
    ? databaseUrl.slice(5)
    : databaseUrl;

  if (databasePath.startsWith('///')) {
    databasePath = databasePath.slice(2);
  }

  return databasePath;
}

function shouldUseDefaultDatabase(databaseUrl: string | undefined) {
  if (!databaseUrl) {
    return true;
  }

  if (!isSqliteLikeDatabase(databaseUrl)) {
    return true;
  }

  const path = resolveSqlitePath(databaseUrl);
  return path.startsWith('/app/');
}

export function buildLocalDevConfig(sourceEnv: EnvMap = process.env): LocalDevConfig {
  const bindHost = trim(sourceEnv.HOSTNAME) || trim(sourceEnv.HOST) || DEFAULT_BIND_HOST;
  const port = coercePort(trim(sourceEnv.PORT) || trim(sourceEnv.APP_PORT));
  const publicOrigin = buildPublicOrigin(sourceEnv, port);
  const databaseUrl = shouldUseDefaultDatabase(trim(sourceEnv.DATABASE_URL))
    ? DEFAULT_DATABASE_URL
    : trim(sourceEnv.DATABASE_URL) ?? DEFAULT_DATABASE_URL;
  const secret = trim(sourceEnv.BETTER_AUTH_SECRET);
  const trustedOrigins = toUniqueList([
    publicOrigin,
    ...parseCsvList(sourceEnv.BETTER_AUTH_TRUSTED_ORIGINS)
  ]).join(',');

  const env: EnvMap = {
    ...sourceEnv,
    BETTER_AUTH_BASE_URL: publicOrigin,
    BETTER_AUTH_SECRET: !secret || secret === PLACEHOLDER_SECRET
      ? LOCAL_DEV_SECRET
      : secret,
    BETTER_AUTH_TRUSTED_ORIGINS: trustedOrigins,
    DATABASE_URL: databaseUrl,
    HOSTNAME: bindHost,
    NEXT_PUBLIC_API_URL: '',
    PORT: port,
    SEC_USER_AGENT: trim(sourceEnv.SEC_USER_AGENT) || DEFAULT_SEC_USER_AGENT,
    WORKFLOW_LOCAL_DATA_DIR: trim(sourceEnv.WORKFLOW_LOCAL_DATA_DIR) || DEFAULT_WORKFLOW_LOCAL_DATA_DIR,
    WORKFLOW_LOCAL_QUEUE_CONCURRENCY:
      trim(sourceEnv.WORKFLOW_LOCAL_QUEUE_CONCURRENCY) || DEFAULT_WORKFLOW_LOCAL_QUEUE_CONCURRENCY,
    WORKFLOW_TARGET_WORLD: 'local'
  };

  return {
    bindHost,
    env,
    overrides: {
      apiBaseChanged: trim(sourceEnv.NEXT_PUBLIC_API_URL) !== undefined,
      authOriginChanged: trim(sourceEnv.BETTER_AUTH_BASE_URL) !== publicOrigin
        || trim(sourceEnv.BETTER_AUTH_URL) !== undefined,
      databaseChanged: databaseUrl !== trim(sourceEnv.DATABASE_URL),
      secretFallbackUsed: env.BETTER_AUTH_SECRET === LOCAL_DEV_SECRET,
      workflowChanged: trim(sourceEnv.WORKFLOW_TARGET_WORLD) !== 'local'
    },
    port,
    publicOrigin
  };
}