package com.gzzn.omms.msgexchange.processing

import com.gzzn.omms.msgexchange.codec.FlopPayload
import com.gzzn.omms.msgexchange.codec.ScheduleBody
import com.gzzn.omms.msgexchange.codec.XmlCodec
import com.gzzn.omms.msgexchange.config.PipelineProps
import com.gzzn.omms.msgexchange.domain.DecodedMessage
import com.gzzn.omms.msgexchange.domain.ErrorClass
import com.gzzn.omms.msgexchange.domain.MsgKind
import com.gzzn.omms.msgexchange.domain.ProcState
import com.gzzn.omms.msgexchange.domain.ProcStatus
import com.gzzn.omms.msgexchange.infra.log.TraceLog
import com.gzzn.omms.msgexchange.infra.persistence.CminmsgInboxRepository
import com.gzzn.omms.msgexchange.infra.persistence.ProcStateRepository
import com.gzzn.omms.msgexchange.infra.retry.ProcFailure
import jakarta.inject.Singleton
import java.time.Clock
import java.time.Duration
import java.time.Instant

/**
 * 处理主泵：一个线程按消息 ID 从小到大一条条处理，保证先来的先处理。
 *
 * 每次 tick 只看当前最小的未完成消息（"队头"）：
 * - 没有待处理消息就睡一个轮询间隔；
 * - 队头失败了还在退避期，就等到能重试的时刻；如果重试次数用尽或滞留太久，
 *   直接转死信，不放任它一直堵着；
 * - 其余情况交给 [MessageProcessor] 处理。
 *
 * 一次只处理一条是刻意的。后面的消息不能越过卡住的队头，否则同一条航班的报文
 * 可能被乱序应用，几十秒后才到的旧报文会把新状态覆盖回去。
 */
@Singleton
class Pump(
    private val procState: ProcStateRepository,
    private val processor: MessageProcessor,
    private val backfill: BackfillService,
    private val props: PipelineProps,
    private val clock: Clock,
) {
    private val log = org.slf4j.LoggerFactory.getLogger(Pump::class.java)

    @Volatile
    private var running = true

    /** 请求停机：当前 tick 跑完就退出。线程中断由 PipelineLifecycle 负责。 */
    fun stop() {
        running = false
    }

    fun loop() {
        while (running) {
            try {
                tick()
            } catch (e: InterruptedException) {
                Thread.currentThread().interrupt()
                return
            } catch (e: Exception) {
                // 兜底：单条消息的失败状态已在 processOne 内记录，这里只避免线程退出
                sleepQuietly(props.pipeline.pollInterval)
            }
        }
    }

    internal fun tick() {
        val head = procState.headUnfinished()
        when {
            head == null -> sleepQuietly(props.pipeline.pollInterval)
            head.state == ProcStatus.FAILED && (head.nextAttemptAt ?: Instant.EPOCH) > clock.instant() ->
                if (poisoned(head)) {
                    log.error("poison -> DEAD msgId={} attempts={} lastError={}", head.msgId, head.attempts, head.lastError)
                    procState.markTerminal(
                        head.msgId, ProcStatus.DEAD,
                        errorClass = ErrorClass.EXHAUSTED,
                        lastError = head.lastError ?: "head-deadline-exceeded",
                        attempts = head.attempts,
                    )
                    backfill.attempt(head.msgId)
                } else {
                    sleepQuietly(Duration.between(clock.instant(), head.nextAttemptAt))
                }
            // 其余情况（新消息，或退避到期的重试）交给处理入口
            else -> processor.processOne(head)
        }
    }

    private fun poisoned(head: ProcState): Boolean =
        head.attempts >= props.pipeline.maxAttempts ||
            Duration.between(head.updatedAt, clock.instant()) > props.pipeline.headDeadline

    private fun sleepQuietly(d: Duration) {
        if (!d.isNegative && !d.isZero) Thread.sleep(d.toMillis().coerceAtLeast(1))
    }
}

/**
 * 处理一条消息：读原文 → 解码 → 绑定业务身份 → 分派给对应处理器 → 提交后回填标记。
 *
 * 业务数据和终态由各处理器在自己的事务里写入。终态一旦落下（成功、跳过或死信），
 * 这里马上试一次把处理标记写回信箱；写不进去也没关系，回填扫描会按退避继续重试。
 *
 * 任何意外异常都算在当前这条消息头上（记 FAILED(INFRA) 后重试），不会把主泵线程带崩。
 * 报文非法和整包协议拒绝不重试，直接进死信等人工处置。
 */
@Singleton
class MessageProcessor(
    private val inbox: CminmsgInboxRepository,
    private val procState: ProcStateRepository,
    private val codec: XmlCodec,
    private val scheduleProcessor: ScheduleProcessor,
    private val flopProcessor: FlopProcessor,
    private val fdelProcessor: FdelProcessor,
    private val adftProcessor: AdftProcessor,
    private val procFailure: ProcFailure,
    private val backfill: BackfillService,
    private val props: PipelineProps,
) {
    private val log = org.slf4j.LoggerFactory.getLogger(MessageProcessor::class.java)

    fun processOne(head: ProcState) {
        TraceLog.withTrace(head.msgId) {
            val terminal = try {
                processInternal(head)
            } catch (e: InterruptedException) {
                Thread.currentThread().interrupt()
                throw e
            } catch (e: Exception) {
                // 边界化：异常归于本条 head，写 FAILED(INFRA)/DEAD，而不是穿出杀 pump
                log.warn("processOne unexpected failure msgId={} ec=INFRA msg={}", head.msgId, e.message ?: e.javaClass.simpleName)
                procFailure.fail(head, ErrorClass.INFRA, e.message ?: e.javaClass.simpleName)
            }
            // 终态已提交：立即尝试一次回填；失败留待回填扫描按退避重试（意图已在终态事务内登记）。
            // 中间态（PENDING/FAILED）不适用（message-lifecycle §5.2）。
            if (terminal) backfill.attempt(head.msgId)
        }
    }

    /** @return 这条消息是否已经落到终态（只有终态才允许回填信箱标记） */
    private fun processInternal(head: ProcState): Boolean {
        // 守卫：手工/遗留 FAILED 行若 attempts 已达上限，直接终态（防止退避到期后无限重试）
        if (head.state == ProcStatus.FAILED && procFailure.scheduler.exhausted(head.attempts)) {
            log.error("head exhausted at entry -> DEAD msgId={} attempts={}", head.msgId, head.attempts)
            procState.markTerminal(
                head.msgId, ProcStatus.DEAD,
                errorClass = ErrorClass.EXHAUSTED,
                lastError = head.lastError ?: "max-attempts",
                attempts = head.attempts,
            )
            return true
        }

        val raw = inbox.rawOf(head.msgId)
        if (raw == null) {
            log.error("raw missing -> DEAD(MALFORMED) msgId={}", head.msgId)
            return deadMalformed(head, "raw-missing")
        }
        val decoded = when (val r = codec.decode(raw)) {
            is com.gzzn.omms.msgexchange.codec.DecodeResult.Ok -> r.message
            is com.gzzn.omms.msgexchange.codec.DecodeResult.Err -> {
                // MALFORMED（报文非法）→ DEAD 不重试；CODEC_ERROR（可随 codec 修复重放）→ FAILED 退避
                if (r.failure.errorClass == ErrorClass.MALFORMED) {
                    log.error("decode MALFORMED -> DEAD msgId={} detail={}", head.msgId, r.failure.detail)
                    return deadMalformed(head, r.failure.detail)
                }
                log.warn("decode {} -> FAILED msgId={} detail={}", r.failure.errorClass, head.msgId, r.failure.detail)
                return procFailure.fail(head, r.failure.errorClass, r.failure.detail)
            }
        }

        // I3：identity 仅首次绑定（head.identityKey == null）；FAILED 重试不重绑
        if (head.identityKey == null) {
            val identity = Identity.of(decoded, props.identity)
            if (!procState.tryBindIdentity(head.msgId, identity)) {
                val owner = procState.ownerOfIdentity(identity) ?: -1L
                log.info("duplicate-of:{} -> SKIPPED msgId={}", owner, head.msgId)
                procState.markTerminal(head.msgId, ProcStatus.SKIPPED, lastError = "duplicate-of:$owner")
                return true
            }
        }

        // 处理器分派：SCHD 日计划主链路（§3.1）/ FLOP / FDEL / ADFT；缺载荷按 MALFORMED 终态
        val result: ApplyResult = when (val kind = decoded.kind) {
            is MsgKind.Schd -> {
                val body = decoded.body as? ScheduleBody
                if (body == null) return deadMalformed(head, "missing-schd-body")
                when (kind.subtype) {
                    MsgKind.SchdSubtype.DNLD, MsgKind.SchdSubtype.RESP ->
                        scheduleProcessor.applyScheduleRecords(head, decoded)
                    MsgKind.SchdSubtype.ADFT -> {
                        val record = body.records.singleOrNull()
                        if (record == null) return deadMalformed(head, "adft-needs-single-fltr")
                        adftProcessor.apply(head, decoded, record)
                    }
                }
            }
            MsgKind.Fdel -> {
                val payload = decoded.body as? FlopPayload
                if (payload == null) return deadMalformed(head, "missing-fdel-flid")
                fdelProcessor.apply(head, decoded, payload)
            }
            is MsgKind.Flop -> {
                val payload = decoded.body as? FlopPayload
                if (payload == null) return deadMalformed(head, "missing-flop-body")
                flopProcessor.apply(head, decoded, payload)
            }
            is MsgKind.Unsupported -> {
                // design.md §2.3：未支持类型 → FAILED(UNSUPPORTED) 退避重试，达阈值转 DEAD；绝不写终态
                log.warn("unsupported type -> FAILED(UNSUPPORTED) msgId={} tag={}", head.msgId, kind.tag)
                return procFailure.fail(head, ErrorClass.UNSUPPORTED, "no-handler:${kind.tag}")
            }
        }

        if (result is ApplyResult.DeadProtocol) {
            // design.md §2.3：整包拒绝 DEAD(PROTOCOL)，立即释放队头，交人工确认
            log.error("DEAD(PROTOCOL) msgId={} reason={} flags={}", head.msgId, result.reason, result.flags)
            procState.markTerminal(
                head.msgId, ProcStatus.DEAD,
                errorClass = ErrorClass.PROTOCOL,
                lastError = result.reason.take(1000),
            )
            return true
        }

        // Succeeded / ReplaySkipped：SUCCEEDED 终态与回填意图已由处理器在自己的事务内落库
        log.info("SUCCEEDED msgId={} kind={}", head.msgId, decoded.typeTag)
        return true
    }

    private fun deadMalformed(head: ProcState, detail: String): Boolean {
        procState.markTerminal(head.msgId, ProcStatus.DEAD, errorClass = ErrorClass.MALFORMED, lastError = detail)
        return true
    }
}