{-|
Module      : KAR.ErrorRecovery
Description : استراتيجية الاسترداد من الأخطاء | Error Recovery Strategy
Copyright   : (c) Ahmad Ali Parr, 2026
License     : Proprietary
Maintainer  : ahmedparr93@gmail.com

Autonomous error recovery strategies. When intent execution fails,
determines recovery action (retry, fallback, or graceful failure).

استراتيجيات الاسترداد الذاتي من الأخطاء
-}

module KAR.ErrorRecovery
    ( selectRecoveryStrategy
    , ErrorContext(..)
    , canRetry
    , shouldFallback
    ) where

import KAR.Types.Intent
import KAR.Types.Decision (RecoveryStrategy(..))
import Data.Word (Word32)

-- | Error context (why execution failed)
data ErrorContext
    = ResourceExhausted      -- ^ Ran out of resources (retry later)
    | TimeoutExpired         -- ^ Execution timeout (retry or fail)
    | AgentCrashed Word32    -- ^ Agent crashed (fallback to another)
    | InvalidPayload         -- ^ Malformed payload (fail immediately)
    | TrustViolation         -- ^ Trust check failed (fail immediately)
    | UnknownError           -- ^ Unknown error (retry once)
    deriving (Eq, Show)

-- | Select recovery strategy based on error context and intent
-- اختيار استراتيجية الاسترداد
selectRecoveryStrategy
    :: ErrorContext
    -> Intent
    -> Int              -- ^ Retry count so far
    -> RecoveryStrategy
selectRecoveryStrategy errCtx intent retryCount =
    case errCtx of
        ResourceExhausted ->
            if retryCount < 3
                then RetryWithBackoff (exponentialBackoff retryCount)
                else GracefulFail

        TimeoutExpired ->
            case intentPriority intent of
                Critical -> RetryImmediate  -- Critical always retries
                High     -> if retryCount < 2
                            then RetryWithBackoff 1000
                            else GracefulFail
                _        -> GracefulFail

        AgentCrashed agentId ->
            -- Try fallback to different agent
            FallbackAgent ((agentId + 1) `mod` 6)

        InvalidPayload ->
            -- No recovery possible for malformed input
            GracefulFail

        TrustViolation ->
            -- Security violation, no retry
            GracefulFail

        UnknownError ->
            if retryCount == 0
                then RetryImmediate
                else GracefulFail

-- | Check if intent can be retried
-- التحقق من إمكانية إعادة المحاولة
canRetry :: ErrorContext -> Bool
canRetry ResourceExhausted = True
canRetry TimeoutExpired    = True
canRetry UnknownError      = True
canRetry _                 = False

-- | Check if should attempt fallback agent
-- التحقق من الحاجة للعامل الاحتياطي
shouldFallback :: ErrorContext -> Bool
shouldFallback (AgentCrashed _) = True
shouldFallback _                = False

-- | Exponential backoff calculation
-- حساب التأخير الأسي
exponentialBackoff :: Int -> Word32
exponentialBackoff n =
    let base = 500  -- 500ms base
        multiplier = 2 ^ min n 5  -- Cap at 2^5 = 32x
    in base * fromIntegral multiplier