{"version":3,"file":"rate-limit.mjs","names":[],"sources":["../../src/hono/rate-limit.ts"],"sourcesContent":["import type { Context, MiddlewareHandler } from 'hono';\nimport { Details } from '../error/detail';\nimport { Status } from '../error/status';\nimport { geolocation } from './geolocation';\n\nexport interface KV {\n setItem(key: string, value: string, expiresIn?: number): Promise;\n getItem(key: string): Promise;\n removeItem(key: string): Promise;\n}\n\ninterface TokenBucketState {\n tokens: number;\n lastRefillTime: number;\n}\n\nexport interface RateLimitOptions {\n kv: KV;\n rate: number;\n capacity: number;\n requested?: number;\n keyPrefix?: string;\n expiresIn?: number;\n getIdentifier?: (c: Context) => string | undefined;\n onRateLimited?: (c: Context, retryAfter: number) => Response | Promise;\n skip?: (c: Context) => boolean | Promise;\n}\n\nexport interface RateLimitResult {\n allowed: boolean;\n remaining: number;\n limit: number;\n reset: number;\n retryAfter?: number;\n}\n\nfunction calculateTokens(\n state: TokenBucketState | null,\n capacity: number,\n rate: number,\n now: number\n): { tokens: number; lastRefillTime: number } {\n if (!state) {\n return { tokens: capacity, lastRefillTime: now };\n }\n\n const elapsed = (now - state.lastRefillTime) / 1000;\n const tokensToAdd = elapsed * rate;\n const newTokens = Math.min(capacity, state.tokens + tokensToAdd);\n\n return {\n tokens: newTokens,\n lastRefillTime: now,\n };\n}\n\nfunction calculateResetTime(currentTokens: number, capacity: number, rate: number): number {\n if (currentTokens >= capacity) return 0;\n return Math.ceil((capacity - currentTokens) / rate);\n}\n\nfunction calculateRetryAfter(currentTokens: number, requested: number, rate: number): number {\n if (currentTokens >= requested) return 0;\n return Math.ceil((requested - currentTokens) / rate);\n}\n\nexport async function checkRateLimit(\n kv: KV,\n identifier: string,\n options: {\n rate: number;\n capacity: number;\n requested?: number;\n keyPrefix?: string;\n expiresIn?: number;\n }\n): Promise {\n const {\n rate,\n capacity,\n requested = 1,\n keyPrefix = 'rate-limit:',\n expiresIn = Math.max(3600, Math.ceil((capacity / rate) * 2)),\n } = options;\n\n const key = `${keyPrefix}${identifier}`;\n const now = Date.now();\n\n const stateStr = await kv.getItem(key);\n const state: TokenBucketState | null = stateStr ? JSON.parse(stateStr) : null;\n\n const { tokens: currentTokens, lastRefillTime } = calculateTokens(state, capacity, rate, now);\n\n const allowed = currentTokens >= requested;\n const newTokens = allowed ? currentTokens - requested : currentTokens;\n\n const newState: TokenBucketState = { tokens: newTokens, lastRefillTime };\n await kv.setItem(key, JSON.stringify(newState), expiresIn);\n\n const result: RateLimitResult = {\n allowed,\n remaining: Math.floor(Math.max(0, newTokens)),\n limit: capacity,\n reset: calculateResetTime(newTokens, capacity, rate),\n };\n\n if (!allowed) {\n result.retryAfter = calculateRetryAfter(currentTokens, requested, rate);\n }\n\n return result;\n}\n\nexport function rateLimit(options: RateLimitOptions): MiddlewareHandler {\n const {\n kv,\n rate,\n capacity,\n requested = 1,\n keyPrefix = 'rate-limit:',\n expiresIn = Math.max(3600, Math.ceil((capacity / rate) * 2)),\n getIdentifier,\n onRateLimited,\n skip,\n } = options;\n\n return async (c, next) => {\n if (skip && (await skip(c))) {\n return next();\n }\n\n const identifier = getIdentifier ? getIdentifier(c) : geolocation(c).ip_address;\n if (!identifier) return next();\n\n const result = await checkRateLimit(kv, identifier, {\n rate,\n capacity,\n requested,\n keyPrefix,\n expiresIn,\n });\n\n c.header('X-RateLimit-Limit', String(result.limit));\n c.header('X-RateLimit-Remaining', String(result.remaining));\n c.header('X-RateLimit-Reset', String(result.reset));\n\n if (!result.allowed) {\n c.header('Retry-After', String(result.retryAfter ?? 1));\n if (onRateLimited) return onRateLimited(c, result.retryAfter ?? 1);\n\n const details = Details.new()\n .errorInfo({ reason: 'RATE_LIMIT_EXCEEDED' })\n .retryInfo({ retryDelay: result.retryAfter ?? 1 });\n\n const message = 'Rate limit exceeded. 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