package logic

import (
	"context"

	"spark-server/internal/module/energy/entity"
	"spark-server/internal/pkg/errs"
)

// LogItem is one energy ledger row for the client bill page.
type LogItem struct {
	Source string `json:"source"`
	Date   int64  `json:"date"`
	Value  int64  `json:"value"`
	ID     int64  `json:"id"`
}

// LogsView is a cursor page of energy details.
type LogsView struct {
	Items      []LogItem `json:"reward_details"`
	NextCursor int64     `json:"next_cursor"`
	IsEnd      bool      `json:"is_end"`
	Energy     int64     `json:"energy"`
}

// Logs lists energy changes newest-first. cursor is the last seen log id (0 = start).
func (s *Service) Logs(ctx context.Context, userID, cursor int64, limit int) (*LogsView, error) {
	if !s.ready() || userID <= 0 {
		return nil, errs.ErrUnauthorized
	}
	limit = entity.ClampLimit(limit)
	rows, err := s.repo.ListEnergyLogs(ctx, userID, cursor, limit+1)
	if err != nil {
		return nil, err
	}
	end := true
	if len(rows) > limit {
		end = false
		rows = rows[:limit]
	}
	items := make([]LogItem, 0, len(rows))
	var next int64
	for _, r := range rows {
		src := r.Source
		if src == "" {
			src = r.Reason
		}
		items = append(items, LogItem{Source: src, Date: r.CreatedMS / 1000, Value: r.Delta, ID: r.ID})
		next = r.ID
	}
	bal, err := s.repo.EnsureWallet(ctx, userID)
	if err != nil {
		return nil, err
	}
	return &LogsView{Items: items, NextCursor: next, IsEnd: end, Energy: bal.Energy}, nil
}