package usecase

import (
	"context"
	"strings"

	"haixun-backend/internal/library/clock"
	app "haixun-backend/internal/library/errors"
	"haixun-backend/internal/library/errors/code"
	jobcron "haixun-backend/internal/model/job/cron"
	"haixun-backend/internal/model/job/domain/entity"
	domrepo "haixun-backend/internal/model/job/domain/repository"
	domusecase "haixun-backend/internal/model/job/domain/usecase"
)

func (u *jobUseCase) ListSchedules(ctx context.Context, scope, scopeID string, page, pageSize int64) ([]*entity.Schedule, int64, int64, int64, int64, error) {
	if page <= 0 {
		page = 1
	}
	if pageSize <= 0 {
		pageSize = 20
	}
	if pageSize > 200 {
		pageSize = 200
	}
	offset := (page - 1) * pageSize
	items, total, err := u.schedules.List(ctx, domrepo.ScheduleListFilter{
		Scope:   scope,
		ScopeID: scopeID,
	}, offset, pageSize)
	if err != nil {
		return nil, 0, 0, 0, 0, err
	}
	totalPages := int64(0)
	if total > 0 {
		totalPages = (total + pageSize - 1) / pageSize
	}
	return items, total, page, pageSize, totalPages, nil
}

func (u *jobUseCase) GetSchedule(ctx context.Context, scheduleID string) (*entity.Schedule, error) {
	return u.schedules.FindByID(ctx, scheduleID)
}

func (u *jobUseCase) CreateSchedule(ctx context.Context, req domusecase.CreateScheduleRequest) (*entity.Schedule, error) {
	templateType := strings.TrimSpace(req.TemplateType)
	scope := strings.TrimSpace(req.Scope)
	scopeID := strings.TrimSpace(req.ScopeID)
	cronExpr := strings.TrimSpace(req.Cron)
	if templateType == "" || scope == "" || scopeID == "" || cronExpr == "" {
		return nil, app.For(code.Job).InputMissingRequired("template_type, scope, scope_id, and cron are required")
	}
	if _, err := u.templates.FindByType(ctx, templateType); err != nil {
		return nil, err
	}

	timezone := req.Timezone
	if timezone == "" {
		timezone = "UTC"
	}
	nextRunAt, err := jobcron.NextRunAt(cronExpr, timezone, clock.Now())
	if err != nil {
		return nil, app.For(code.Job).InputInvalidFormat(err.Error())
	}

	schedule := &entity.Schedule{
		TemplateType:    templateType,
		Scope:           scope,
		ScopeID:         scopeID,
		Enabled:         req.Enabled,
		Cron:            cronExpr,
		Timezone:        timezone,
		PayloadTemplate: req.PayloadTemplate,
		NextRunAt:       nextRunAt,
	}
	return u.schedules.Create(ctx, schedule)
}

func (u *jobUseCase) UpdateSchedule(ctx context.Context, req domusecase.UpdateScheduleRequest) (*entity.Schedule, error) {
	schedule, err := u.schedules.FindByID(ctx, req.ID)
	if err != nil {
		return nil, err
	}
	if cronExpr := strings.TrimSpace(req.Cron); cronExpr != "" {
		schedule.Cron = cronExpr
	}
	if tz := strings.TrimSpace(req.Timezone); tz != "" {
		schedule.Timezone = tz
	}
	if req.PayloadTemplate != nil {
		schedule.PayloadTemplate = req.PayloadTemplate
	}
	if req.Enabled != nil {
		schedule.Enabled = *req.Enabled
	}

	nextRunAt, err := jobcron.NextRunAt(schedule.Cron, schedule.Timezone, clock.Now())
	if err != nil {
		return nil, app.For(code.Job).InputInvalidFormat(err.Error())
	}
	schedule.NextRunAt = nextRunAt
	return u.schedules.Update(ctx, schedule)
}

func (u *jobUseCase) EnableSchedule(ctx context.Context, scheduleID string) (*entity.Schedule, error) {
	schedule, err := u.schedules.FindByID(ctx, scheduleID)
	if err != nil {
		return nil, err
	}
	schedule.Enabled = true
	nextRunAt, err := jobcron.NextRunAt(schedule.Cron, schedule.Timezone, clock.Now())
	if err != nil {
		return nil, app.For(code.Job).InputInvalidFormat(err.Error())
	}
	schedule.NextRunAt = nextRunAt
	return u.schedules.Update(ctx, schedule)
}

func (u *jobUseCase) DisableSchedule(ctx context.Context, scheduleID string) (*entity.Schedule, error) {
	schedule, err := u.schedules.FindByID(ctx, scheduleID)
	if err != nil {
		return nil, err
	}
	schedule.Enabled = false
	return u.schedules.Update(ctx, schedule)
}

func (u *jobUseCase) RunSchedulerTick(ctx context.Context, holder string) (int, error) {
	ok, err := u.queue.TrySchedulerLock(ctx, holder, 55)
	if err != nil {
		return 0, err
	}
	if !ok {
		return 0, nil
	}
	defer func() { _ = u.queue.ReleaseSchedulerLock(ctx, holder) }()

	now := clock.NowUnixNano()
	due, err := u.schedules.FindDue(ctx, now, 50)
	if err != nil {
		return 0, err
	}

	created := 0
	var firstErr error
	for _, schedule := range due {
		payload := buildScheduleRunPayload(schedule, now)
		if _, err := u.CreateRun(ctx, domusecase.CreateRunRequest{
			TemplateType: schedule.TemplateType,
			Scope:        schedule.Scope,
			ScopeID:      schedule.ScopeID,
			Payload:      payload,
		}); err != nil {
			if firstErr == nil {
				firstErr = err
			}
			continue
		}
		created++

		lastRun := now
		schedule.LastRunAt = &lastRun
		nextRunAt, calcErr := jobcron.NextRunAt(schedule.Cron, schedule.Timezone, clock.Now())
		if calcErr != nil {
			continue
		}
		schedule.NextRunAt = nextRunAt
		_, _ = u.schedules.Update(ctx, schedule)
	}
	return created, firstErr
}