package handler

import (
	"context"
	"net/http"
	"time"

	"predictor-refactored/internal/prediction"
	api "predictor-refactored/pkg/rest"

	"go.uber.org/zap"
)

var _ api.Handler = (*Handler)(nil)

// Handler implements the ogen-generated api.Handler interface.
type Handler struct {
	svc Service
	log *zap.Logger
}

// New creates a new Handler.
func New(svc Service, log *zap.Logger) *Handler {
	return &Handler{svc: svc, log: log}
}

// PerformPrediction implements the prediction endpoint.
func (h *Handler) PerformPrediction(ctx context.Context, params api.PerformPredictionParams) (*api.PredictionResponse, error) {
	if !h.svc.Ready() {
		return nil, newError(http.StatusServiceUnavailable, "no dataset loaded, service is starting up")
	}

	ds := h.svc.Dataset()
	if ds == nil {
		return nil, newError(http.StatusServiceUnavailable, "dataset unavailable")
	}

	dsEpoch := float64(ds.DSTime.Unix())

	// Parse parameters with defaults
	profile := "standard_profile"
	if p, ok := params.Profile.Get(); ok {
		profile = string(p)
	}

	ascentRate := 5.0
	if v, ok := params.AscentRate.Get(); ok {
		ascentRate = v
	}

	burstAltitude := 28000.0
	if v, ok := params.BurstAltitude.Get(); ok {
		burstAltitude = v
	}

	descentRate := 5.0
	if v, ok := params.DescentRate.Get(); ok {
		descentRate = v
	}

	launchAlt := 0.0
	if v, ok := params.LaunchAltitude.Get(); ok {
		launchAlt = v
	}

	// Normalize longitude to [0, 360)
	lng := params.LaunchLongitude
	if lng < 0 {
		lng += 360.0
	}

	launchTime := float64(params.LaunchDatetime.Unix())

	warnings := &prediction.Warnings{}

	// Build profile chain
	elev := h.svc.Elevation()
	var stages []prediction.Stage
	switch profile {
	case "standard_profile":
		stages = prediction.StandardProfile(
			ascentRate, burstAltitude, descentRate,
			ds, dsEpoch, warnings, elev)
	case "float_profile":
		floatAlt := 25000.0
		if v, ok := params.FloatAltitude.Get(); ok {
			floatAlt = v
		}
		stopTime := params.LaunchDatetime.Add(24 * time.Hour)
		if v, ok := params.StopDatetime.Get(); ok {
			stopTime = v
		}
		stages = prediction.FloatProfile(
			ascentRate, floatAlt, stopTime,
			ds, dsEpoch, warnings)
	default:
		return nil, newError(http.StatusBadRequest, "unknown profile: "+profile)
	}

	// Run prediction
	startTime := time.Now().UTC()
	results := prediction.RunPrediction(launchTime, params.LaunchLatitude, lng, launchAlt, stages)
	completeTime := time.Now().UTC()

	// Build response
	stageNames := []string{"ascent", "descent"}
	if profile == "float_profile" {
		stageNames = []string{"ascent", "float"}
	}

	var predItems []api.PredictionResponsePredictionItem
	for i, sr := range results {
		stageName := "ascent"
		if i < len(stageNames) {
			stageName = stageNames[i]
		}

		var stageEnum api.PredictionResponsePredictionItemStage
		switch stageName {
		case "ascent":
			stageEnum = api.PredictionResponsePredictionItemStageAscent
		case "descent":
			stageEnum = api.PredictionResponsePredictionItemStageDescent
		case "float":
			stageEnum = api.PredictionResponsePredictionItemStageFloat
		}

		var traj []api.PredictionResponsePredictionItemTrajectoryItem
		for _, pt := range sr.Points {
			ptLng := pt.Lng
			if ptLng > 180 {
				ptLng -= 360
			}
			traj = append(traj, api.PredictionResponsePredictionItemTrajectoryItem{
				Datetime:  time.Unix(int64(pt.T), 0).UTC(),
				Latitude:  pt.Lat,
				Longitude: ptLng,
				Altitude:  pt.Alt,
			})
		}

		predItems = append(predItems, api.PredictionResponsePredictionItem{
			Stage:      stageEnum,
			Trajectory: traj,
		})
	}

	resp := &api.PredictionResponse{
		Prediction: predItems,
		Metadata: api.PredictionResponseMetadata{
			StartDatetime:    startTime,
			CompleteDatetime: completeTime,
		},
	}

	// Echo request
	resp.Request = api.NewOptPredictionResponseRequest(api.PredictionResponseRequest{
		Dataset:         api.NewOptString(ds.DSTime.Format("2006-01-02T15:04:05Z")),
		LaunchLatitude:  api.NewOptFloat64(params.LaunchLatitude),
		LaunchLongitude: api.NewOptFloat64(params.LaunchLongitude),
		LaunchDatetime:  api.NewOptString(params.LaunchDatetime.Format(time.RFC3339)),
		LaunchAltitude:  params.LaunchAltitude,
	})

	// Warnings
	warnMap := warnings.ToMap()
	if len(warnMap) > 0 {
		resp.Warnings = api.NewOptPredictionResponseWarnings(api.PredictionResponseWarnings{})
	}

	h.log.Info("prediction complete",
		zap.String("profile", profile),
		zap.Int("stages", len(results)),
		zap.Duration("elapsed", completeTime.Sub(startTime)))

	return resp, nil
}

// ReadinessCheck implements the health check endpoint.
func (h *Handler) ReadinessCheck(ctx context.Context) (*api.ReadinessResponse, error) {
	resp := &api.ReadinessResponse{}

	if h.svc.Ready() {
		resp.Status = api.ReadinessResponseStatusOk
		if dsTime, ok := h.svc.DatasetTime(); ok {
			resp.DatasetTime = api.NewOptDateTime(dsTime)
		}
	} else {
		resp.Status = api.ReadinessResponseStatusNotReady
		resp.ErrorMessage = api.NewOptString("no dataset loaded")
	}

	return resp, nil
}

// NewError creates an ErrorStatusCode from an error returned by a handler.
func (h *Handler) NewError(ctx context.Context, err error) *api.ErrorStatusCode {
	if statusErr, ok := err.(*api.ErrorStatusCode); ok {
		return statusErr
	}

	h.log.Error("unhandled error", zap.Error(err))
	return newError(http.StatusInternalServerError, err.Error())
}

func newError(status int, description string) *api.ErrorStatusCode {
	return &api.ErrorStatusCode{
		StatusCode: status,
		Response: api.Error{
			Error: api.ErrorError{
				Type:        http.StatusText(status),
				Description: description,
			},
		},
	}
}