package report

import (
	"fmt"
	"time"
)

func Resolve(id ID, req ResolveRequest) (Resolved, error) {
	return DefaultRegistry().Resolve(id, req)
}

func (r Registry) Resolve(id ID, req ResolveRequest) (Resolved, error) {
	definition, err := r.Lookup(id)
	if err != nil {
		return Resolved{}, err
	}
	return r.resolveDefinition(definition, req)
}

func (r Registry) BatchReports(batch Batch, req ResolveRequest) ([]Resolved, error) {
	if req.Location == nil {
		req.Location = time.UTC
	}
	if req.Now.IsZero() {
		req.Now = time.Now()
	}
	switch batch {
	case Morning:
		ids := []ID{Today, ThreeDay}
		if req.Now.In(req.Location).Weekday() != time.Sunday {
			ids = append(ids, Weekend)
		}
		return r.resolveIDs(ids, req)
	case Evening:
		return r.resolveIDs([]ID{Tomorrow}, req)
	default:
		return nil, fmt.Errorf("unknown batch %q", batch)
	}
}

func (r Registry) resolveIDs(ids []ID, req ResolveRequest) ([]Resolved, error) {
	resolved := make([]Resolved, 0, len(ids))
	for _, id := range ids {
		item, err := r.Resolve(id, req)
		if err != nil {
			return nil, err
		}
		resolved = append(resolved, item)
	}
	return resolved, nil
}

func (r Registry) resolveDefinition(definition Definition, req ResolveRequest) (Resolved, error) {
	if req.Location == nil {
		req.Location = time.UTC
	}
	if req.Now.IsZero() {
		req.Now = time.Now()
	}
	period, err := definition.ResolvePeriod(req)
	if err != nil {
		return Resolved{}, err
	}
	return Resolved{
		Definition:  definition,
		GeneratedAt: req.Now,
		Timezone:    req.Location.String(),
		ValidPeriod: period,
	}, nil
}