package stream

import (
	"chat-agent-system/internal/errcode"
	"errors"
	"io"
	"net"
	"strings"
	"unicode/utf8"
)

// ClassifyError maps a raw error into structured ErrorInfo using heuristic rules.
func ClassifyError(err error, phaseID, requestID, sessionID, workspaceID string) ErrorInfo {
	if err == nil {
		err = errors.New("unknown error")
	}

	msg := strings.ToLower(err.Error())

	info := ErrorInfo{
		PhaseID:     phaseID,
		RequestID:   requestID,
		SessionID:   sessionID,
		WorkspaceID: workspaceID,
	}

	raw := err.Error()
	if !containsInternalLeak(raw) {
		info.Upstream = truncateRunes(raw, 80)
	}

	if def, ok := errcode.FromError(err); ok {
		info.Code = def.ID
		info.Class = ErrorClass(def.Class)
		if info.Class == "" {
			info.Class = ErrorClassFatal
		}
		info.UserMessage = def.Message
		info.Guide = def.Guide
		if len(def.Actions) == 0 {
			info.Actions = []string{}
		} else {
			info.Actions = append([]string(nil), def.Actions...)
		}
		info.Message = info.UserMessage
		return info
	}

	switch {
	case strings.Contains(msg, "编辑中") || strings.Contains(msg, "禁止并行修改") || strings.Contains(msg, "edit lease"):
		info.Code = "DOC_BUSY"
		info.Class = ErrorClassFatal
		info.UserMessage = "该文档正在由项目助手或其他用户编辑中；当前请求未执行，请等待现有任务完成"
		info.Actions = []string{}

	case isDocumentLedgerError(msg):
		info.Code = "DOC_LEDGER_ERROR"
		info.Class = ErrorClassFatal
		info.UserMessage = "文档职责账本写入失败，请重新开始会话；若反复出现请联系管理员"
		info.Actions = []string{"restart"}

	case isTimeoutError(msg):
		info.Code = "CHAT_TIMEOUT"
		info.Class = ErrorClassTransient
		info.UserMessage = "生成回复超时，请稍后重试"
		info.Actions = []string{"retry"}

	case isNetworkError(err, msg):
		info.Code = "NETWORK_ERROR"
		info.Class = ErrorClassTransient
		info.UserMessage = "网络连接异常，请稍后重试"
		info.Actions = []string{"retry"}

	case strings.Contains(msg, "runner data root mismatch"):
		info.Code = "RUNNER_MISMATCH"
		info.Class = ErrorClassFatal
		info.UserMessage = "模型执行环境与数据目录不一致，请联系管理员检查部署配置"
		info.Actions = []string{}

	case isRunnerContractError(msg):
		// Permanent runner wire/contract failures must not look "resumable".
		info.Code = "RUNNER_RESULT_REJECTED"
		info.Class = ErrorClassFatal
		info.UserMessage = "助手执行结果校验失败，请重新开始任务"
		info.Actions = []string{"restart"}

	case workspaceID != "":
		info.Code = "TASK_INTERRUPTED"
		info.Class = ErrorClassResumable
		info.UserMessage = "任务执行中断，可继续或重新开始"
		info.Actions = []string{"continue", "restart"}

	default:
		info.Code = "INTERNAL_ERROR"
		info.Class = ErrorClassFatal
		info.UserMessage = "系统内部错误，请重新开始会话"
		info.Actions = []string{"restart"}
	}

	info.Message = info.UserMessage
	return info
}

func containsInternalLeak(s string) bool {
	low := strings.ToLower(s)
	for _, n := range []string{"sql", "pq:", "token", "password", "/home/", "prompt"} {
		if strings.Contains(low, n) || strings.Contains(s, n) {
			return true
		}
	}
	return false
}

func isDocumentLedgerError(msg string) bool {
	return strings.Contains(msg, "persist document ledger") ||
		strings.Contains(msg, "sqlstate 23503") ||
		strings.Contains(msg, "foreign key constraint") ||
		strings.Contains(msg, "document_records_reviewer_id_fkey") ||
		strings.Contains(msg, "document_records_author_id_fkey") ||
		strings.Contains(msg, "document_records_approver_id_fkey")
}

func isRunnerContractError(msg string) bool {
	return strings.Contains(msg, "typed result rejected") ||
		strings.Contains(msg, "runner result body too large")
}

func isTimeoutError(msg string) bool {
	return strings.Contains(msg, "timeout") ||
		strings.Contains(msg, "deadline") ||
		strings.Contains(msg, "timed out")
}

func isNetworkError(err error, msg string) bool {
	var netErr net.Error
	if errors.As(err, &netErr) {
		if netErr.Timeout() || netErr.Temporary() {
			return true
		}
	}

	var opErr *net.OpError
	if errors.As(err, &opErr) {
		if opErr.Op == "dial" {
			return true
		}
	}

	networkHints := []string{
		"connection refused",
		"eof",
		"broken pipe",
	}
	for _, hint := range networkHints {
		if strings.Contains(msg, hint) {
			return true
		}
	}

	if errors.Is(err, io.EOF) {
		return true
	}

	return false
}

func truncateRunes(s string, maxRunes int) string {
	if maxRunes <= 0 || s == "" {
		return s
	}
	if utf8.RuneCountInString(s) <= maxRunes {
		return s
	}
	runes := []rune(s)
	return string(runes[:maxRunes])
}