package orbit

import (
	"context"
	"encoding/json"
	"errors"
	"time"
)

// WorkflowEventSummary 只表示已保存的事件，不把当前状态或当前激活反填到历史。
type WorkflowEventSummary struct {
	ID                string    `json:"id"`                        // ID 原不可变状态事件标识。
	WorkflowID        string    `json:"workflow_id"`               // WorkflowID 已核验授权的流程归属。
	AggregateKind     string    `json:"aggregate_kind"`            // AggregateKind workflow、workflow_step或workflow_signal。
	AggregateID       string    `json:"aggregate_id"`              // AggregateID 产生事件的实例、步骤或信号身份。
	AggregateRevision uint64    `json:"aggregate_revision,string"` // AggregateRevision 来源资源版本，各资源独立，不是全局序号。
	Type              string    `json:"type"`                      // Type 原始事件类型，不按当前状态改写。
	StateScope        string    `json:"state_scope"`               // StateScope WORKFLOW、STEP或SIGNAL，说明State记录的是哪类对象。
	State             string    `json:"state"`                     // State 该事件保存的状态，不代表对象当前状态。
	StepKey           string    `json:"step_key,omitempty"`        // StepKey 步骤事件的固定定义名称；其他事件省略。
	OccurredAt        time.Time `json:"occurred_at"`               // OccurredAt 数据库事件记录时间，UTC微秒精度，不是外部业务发生时间或提交水位。
}
type WorkflowEventPage struct {
	WorkflowID string                 `json:"workflow_id"`           // WorkflowID 本页授权的实例身份。
	Revision   uint64                 `json:"revision,string"`       // Revision 本页读取时实例版本，不能作为信号或步骤事件的消费水位。
	Items      []WorkflowEventSummary `json:"items"`                 // Items 按记录时间和ID倒序的有界摘要，空列表为[]。
	NextCursor string                 `json:"next_cursor,omitempty"` // NextCursor 绑定实例与事件查询种类，不承诺跨页快照。
}
type WorkflowEventDetail struct {
	WorkflowEventSummary
	Payload json.RawMessage `json:"payload"` // Payload 原不可变事件元数据，最多64KiB；嵌套数字保留原文本，输入/结果另走资源详情。
}

// ListWorkflowEvents 读取实例、步骤和信号的不可变状态事件，需要workflows:audit:read。
func (c *Client) ListWorkflowEvents(ctx context.Context, id string, in HistoryPageRequest) (WorkflowEventPage, error) {
	var out WorkflowEventPage
	if !validID(id) {
		return out, errors.New("invalid workflow id")
	}
	query, err := historyPageQuery(in)
	if err != nil {
		return out, err
	}
	if err = c.call(ctx, "GET", "/v1/workflows/"+id+"/events"+query, "", nil, &out); err != nil {
		return WorkflowEventPage{}, err
	}
	if out.WorkflowID != id || out.Revision == 0 || out.Items == nil || !historyResponseSize(len(out.Items), in) {
		return WorkflowEventPage{}, errors.New("invalid workflow event page")
	}
	for i, e := range out.Items {
		if !validWorkflowEvent(e, id) || i > 0 && (e.OccurredAt.After(out.Items[i-1].OccurredAt) || e.OccurredAt.Equal(out.Items[i-1].OccurredAt) && e.ID >= out.Items[i-1].ID) {
			return WorkflowEventPage{}, errors.New("invalid workflow event summary or ordering")
		}
	}
	return out, nil
}
func validWorkflowEvent(e WorkflowEventSummary, id string) bool {
	if e.WorkflowID != id || !validID(e.ID) || !validID(e.AggregateID) || e.AggregateRevision == 0 || e.Type == "" || e.State == "" || e.OccurredAt.IsZero() {
		return false
	}
	switch e.AggregateKind {
	case "workflow":
		if e.AggregateID != id {
			return false
		}
	case "workflow_step":
		if !workflowVersionName(e.StepKey) {
			return false
		}
	case "workflow_signal":
	default:
		return false
	}
	return e.StateScope == "WORKFLOW" || e.StateScope == "STEP" || e.StateScope == "SIGNAL"
}
func (c *Client) GetWorkflowEvent(ctx context.Context, id, event string) (WorkflowEventDetail, error) {
	var out WorkflowEventDetail
	if !validID(id) || !validID(event) {
		return out, errors.New("invalid workflow event identity")
	}
	if err := c.call(ctx, "GET", "/v1/workflows/"+id+"/events/"+event, "", nil, &out); err != nil {
		return WorkflowEventDetail{}, err
	}
	if out.ID != event || !validWorkflowEvent(out.WorkflowEventSummary, id) || len(out.Payload) == 0 || len(out.Payload) > 65536 || !json.Valid(out.Payload) {
		return WorkflowEventDetail{}, errors.New("invalid workflow event detail")
	}
	return out, nil
}