package api

import (
	"context"
	"fmt"
	"net/http"

	"predictor-refactored/internal/windviz"
	apirest "predictor-refactored/pkg/rest"
)

// GetWindMeta implements GET /api/v1/wind/meta.
func (h *Handler) GetWindMeta(_ context.Context) (*apirest.WindMeta, error) {
	field := h.mgr.Active()
	if field == nil {
		return nil, apiError(http.StatusServiceUnavailable, "no dataset loaded")
	}
	return &apirest.WindMeta{
		Source:             field.Source(),
		Epoch:              field.Epoch().UTC(),
		DefaultStep:        1.0,
		MinStep:            0.25,
		SuggestedAltitudes: []int{0, 1000, 5000, 10000, 15000, 20000, 30000},
		Bbox:               apirest.Region{MinLat: -90, MaxLat: 90, MinLng: 0, MaxLng: 360},
	}, nil
}

// GetWindField implements GET /api/v1/wind/field.
func (h *Handler) GetWindField(_ context.Context, params apirest.GetWindFieldParams) ([]apirest.WindComponent, error) {
	field := h.mgr.Active()
	if field == nil {
		return nil, apiError(http.StatusServiceUnavailable, "no dataset loaded")
	}

	when := field.Epoch()
	if t, ok := params.Time.Get(); ok {
		when = t
	}
	req := windviz.Request{
		Time:     float64(when.Unix()),
		Altitude: params.Altitude.Or(0),
		MinLat:   params.MinLat.Or(0),
		MaxLat:   params.MaxLat.Or(0),
		MinLng:   params.MinLng.Or(0),
		MaxLng:   params.MaxLng.Or(0),
		Step:     params.Step.Or(0),
	}

	key := fmt.Sprintf("%s|%v|%.3f|%.3f|%.3f|%.3f|%.3f|%.3f",
		field.Source(), req.Time, req.Altitude, req.MinLat, req.MaxLat, req.MinLng, req.MaxLng, req.Step)
	if h.cache != nil {
		if cached, ok := h.cache.Get(key); ok {
			return windFieldToAPI(cached), nil
		}
	}

	out, err := windviz.Rasterize(field, req)
	if err != nil {
		return nil, apiError(http.StatusBadRequest, err.Error())
	}
	if h.cache != nil {
		h.cache.Put(key, out)
	}
	return windFieldToAPI(out), nil
}

// windFieldToAPI maps a rasterized field to the generated component slice.
func windFieldToAPI(f windviz.Field) []apirest.WindComponent {
	out := make([]apirest.WindComponent, 0, len(f))
	for _, c := range f {
		out = append(out, apirest.WindComponent{
			Header: apirest.WindHeader{
				ParameterCategory:   c.Header.ParameterCategory,
				ParameterNumber:     c.Header.ParameterNumber,
				ParameterNumberName: apirest.NewOptString(c.Header.ParameterNumberName),
				ParameterUnit:       apirest.NewOptString(c.Header.ParameterUnit),
				Nx:                  c.Header.Nx,
				Ny:                  c.Header.Ny,
				Lo1:                 c.Header.Lo1,
				La1:                 c.Header.La1,
				Lo2:                 c.Header.Lo2,
				La2:                 c.Header.La2,
				Dx:                  c.Header.Dx,
				Dy:                  c.Header.Dy,
				RefTime:             c.Header.RefTime,
				ForecastTime:        c.Header.ForecastTime,
			},
			Data: c.Data,
		})
	}
	return out
}