msgexchange-v2/src/main/kotlin/com/gzzn/omms/msgexchange/codec/JacksonXmlCodec.kt

package com.gzzn.omms.msgexchange.codec

import com.fasterxml.jackson.databind.DeserializationFeature
import com.fasterxml.jackson.databind.JsonMappingException
import com.fasterxml.jackson.module.kotlin.registerKotlinModule
import com.fasterxml.jackson.dataformat.xml.XmlFactory
import com.fasterxml.jackson.dataformat.xml.XmlMapper
import com.gzzn.omms.msgexchange.domain.DecodedMessage
import com.gzzn.omms.msgexchange.domain.ErrorClass
import com.gzzn.omms.msgexchange.domain.MetaFields
import com.gzzn.omms.msgexchange.domain.MsgKind
import jakarta.inject.Singleton
import javax.xml.stream.XMLInputFactory

/** XML codec for the SIS wire contract; XML DTO binding is kept separate from domain payloads. */
@Singleton
class JacksonXmlCodec : XmlCodec {
    private val mapper: XmlMapper = XmlMapper(
        XmlFactory(
            XMLInputFactory.newInstance().apply {
                setProperty(XMLInputFactory.SUPPORT_DTD, false)
                setProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, false)
            },
        ),
    ).apply {
        registerKotlinModule()
        // SIS explicitly permits fields unused by a subsystem; wire DTOs document that policy.
        configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
    }

    override fun decode(rawXml: String): DecodeResult {
        val trimmed = rawXml.trim()
        if (trimmed.isEmpty() || !trimmed.startsWith("<")) {
            return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "empty-or-non-xml"))
        }
        val msg = try {
            mapper.readValue(trimmed, SisMessageXml::class.java)
        } catch (e: JsonMappingException) {
            // META 层绑定失败=发送方违反必填契约（MALFORMED）；体层（SCHD/FLOP）结构不匹配
            // =wire 结构超出编解码器当前绑定能力（CODEC_ERROR：退避重试，修复后可重放，docs/implementation.md「状态与错误分类」）。
            val first = e.path.firstOrNull()?.fieldName ?: ""
            if (first.equals("meta", ignoreCase = true)) {
                return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "xml-meta:${e.originalMessage.take(200)}"))
            }
            return DecodeResult.Err(DecodeFailure(ErrorClass.CODEC_ERROR, "xml-mapping:${e.originalMessage.take(200)}"))
        } catch (e: Exception) {
            return DecodeResult.Err(
                DecodeFailure(ErrorClass.MALFORMED, "xml-parse:${e.message?.take(200) ?: e.javaClass.simpleName}"),
            )
        }
        val meta = msg.meta
            ?: return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "missing-meta"))
        val sndr = meta.sndr?.trim()?.takeIf { it.isNotEmpty() }
            ?: return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "missing-sndr"))
        val seqn = meta.seqn
            ?: return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "missing-or-invalid-seqn"))
        val dttm = meta.dttm
            ?: return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "missing-or-invalid-dttm"))
        val type = meta.type?.trim()?.uppercase()
            ?: return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "missing-type"))
        val styp = meta.styp?.trim()?.uppercase()
            ?: return DecodeResult.Err(DecodeFailure(ErrorClass.MALFORMED, "missing-styp"))

        val kind = kindOf(type, styp)
        val body: Any? = when (kind) {
            is MsgKind.Schd -> msg.schd?.let(SisWireMapper::scheduleBody)
            is MsgKind.Flop -> msg.flop?.let(SisWireMapper::flopPayload)
            MsgKind.Fdel -> msg.flop?.let(SisWireMapper::flopPayload)
            is MsgKind.Unsupported -> null
        }

        return DecodeResult.Ok(
            DecodedMessage(
                meta = MetaFields(sndr = sndr, type = type, styp = styp, seqn = seqn, dttm = dttm),
                kind = kind,
                rawXml = trimmed,
                body = body,
            ),
        )
    }

    override fun encodeRqrd(kind: String, rangeJson: String): String =
        """<?xml version="1.0" encoding="UTF-8"?><MSG><META><TYPE>RQFD</TYPE></META></MSG>"""

    /**
     * 子类型分派必须是**白名单**：未知的 SCHD 子类型不能静默当成全量日计划（DNLD）——
     * 那会让一条本该"暂不支持、等人工处置"的报文走最重的整包合并写入路径。
     * 空 STYP 按 legacy 约定视为 DNLD（该约定待与 SIS 逐类对拍确认，见 Q3）。
     */
    private fun kindOf(type: String, styp: String): MsgKind = when (type) {
        "SCHD" -> when (styp) {
            "RESP" -> MsgKind.Schd(MsgKind.SchdSubtype.RESP)
            "ADFT" -> MsgKind.Schd(MsgKind.SchdSubtype.ADFT)
            "DNLD", "" -> MsgKind.Schd(MsgKind.SchdSubtype.DNLD)
            else -> MsgKind.Unsupported("SCHD-$styp")
        }
        "FLOP" -> if (styp == "FDEL") MsgKind.Fdel else MsgKind.Flop(styp)
        else -> MsgKind.Unsupported("$type-$styp")
    }
}