package cmd

import (
	"context"
	"fmt"
	"os"
	"strings"
	"time"

	"bnbl.io/wx/metar"
	"github.com/spf13/cobra"
)

// wx metar --past 1h kbos
// wx metar --past 3h kbos kbed
// wx metar --past 1h @MA
// wx metar --since yesterday --until now kbos
// wx metar --since yesterday --until now --rect 0,0,1,1
// wx metar --past 1h --rect 0,0,1,1
// wx metar --past 1h --radial 90,0,0
// wx metar --past 6h --most-recent-by-station=constraint --path-dist 50 --waypoint ksea --waypoint kbos --min-dist 3

type relTime struct {
	t time.Time
}

func (t *relTime) String() string {
	return t.t.String()
}

func (t *relTime) Set(s string) (err error) {
	// first, see if s is a duration that we can use relative to now, e.g.
	// "--since 3d" means since 3 days ago.
	if d, err := time.ParseDuration(s); err == nil {
		t.t = time.Now().Add(-1 * d)
		return nil
	}

	// next, try to parse it in a series of formats
	t.t, err = time.Parse("2006-01-02T15:04:05", s)
	return
}

func (t *relTime) Type() string {
	return "relative time"
}

type rectangle struct {
	minLat, minLon, maxLat, maxLon float64
}

func (r *rectangle) String() string {
	return fmt.Sprintf("%f,%f,%f,%f", r.minLat, r.minLon, r.maxLat, r.maxLon)
}

func (r *rectangle) Set(s string) error {
	n, err := fmt.Sscanf(s, "%f,%f,%f,%f", &r.minLat, &r.minLon, &r.maxLat, &r.maxLon)
	if err != nil {
		return err
	}
	if n != 4 {
		return fmt.Errorf("excpected 4 values but got %d", n)
	}
	return nil
}

func (r *rectangle) Type() string {
	return "rect"
}

func (r *rectangle) IsZero() bool {
	return r.minLat == 0 && r.minLon == 0 && r.maxLat == 0 && r.maxLon == 0
}

type ring struct {
	radius, lat, lon float64
}

func (r *ring) String() string {
	return fmt.Sprintf("%f,%f,%f", r.radius, r.lat, r.lon)
}

func (r *ring) Set(s string) error {
	n, err := fmt.Sscanf(s, "%f,%f,%f", &r.radius, &r.lat, &r.lon)
	if err != nil {
		return err
	}
	if n != 3 {
		return fmt.Errorf("expected a radius, lat, and lon, but got %d values", n)
	}
	return nil
}

func (r *ring) Type() string {
	return "radial"
}

func (r *ring) IsZero() bool {
	return r.radius == 0 && r.lat == 0 && r.lon == 0
}

var (
	since, until        relTime
	past                time.Duration
	mostRecentByStation string
	mostRecent          bool
	rect                rectangle
	radial              ring
	pathDist            float64
	waypoints           []string
	minDist             float64
)

func init() {
	rootCmd.AddCommand(metarCmd)

	// time constraints
	metarCmd.Flags().Var(
		&since, "since",
		`Starting time for METARs (e.g. "2020-01-01T01:31:00" or "3h"), used in
conjunction with --until`)
	metarCmd.Flags().Var(
		&until, "until",
		`Ending time for METARs (e.g. "2020-01-01T01:31:00" or "3h"), used in
conjunction with --since`)
	metarCmd.Flags().DurationVar(
		&past, "past", time.Hour,
		`Duration to retrieve METARs since (e.g. "3h")`)

	// location constraints
	metarCmd.Flags().Var(
		&rect, "rect",
		`A lat-lon rect to search within (minLat,minLon,maxLat,maxLon) e.g.
"40,-71,41,-70"`)
	metarCmd.Flags().Var(
		&radial, "radial",
		`A distance around a radius to search within (dist,centerLat,centerLon)
e.g. "3.5,40,-71"`)
	metarCmd.Flags().Float64Var(
		&pathDist, "path-dist", 0,
		"The distance along the flight path to search METARs for")
	metarCmd.Flags().StringSliceVar(
		&waypoints, "waypoint", []string{},
		`Multiple waypoint arguments specify the waypoints that make up a flight
path, ordered from origin to destination. They may be specified as ICAO
identifiers e.g. "KBOS", or as lon-lat pairs, e.g. "-71,40".`)
	metarCmd.Flags().Float64Var(
		&minDist, "min-dist", 0,
		`The minimum distance in degrees latitude or longitude between stations
reported. A higher value results in less dense results.`)

	// result count limiting
	metarCmd.Flags().StringVar(
		&mostRecentByStation, "most-recent-by-station", "constraint",
		`Method for fetching most recent for each station ("constraint",
"postfilter", "false")`)
	metarCmd.Flags().BoolVar(
		&mostRecent, "most-recent", false,
		`Only fetch the single most recently-issued METAR of all the selected
stations`)
}

var metarCmd = &cobra.Command{
	Use:   "metar",
	Short: "Fetch METARs",
	Long:  "Fetch METARs matching the supplied criteria from the TDS",
	Run: func(cmd *cobra.Command, args []string) {
		reqArgs := []func(*metar.Request){}

		if len(args) > 0 {
			reqArgs = append(reqArgs, metar.StationString(strings.Join(args, " ")))
		}

		if !since.t.IsZero() || !until.t.IsZero() {
			reqArgs = append(reqArgs, metar.TimeRange(since.t, until.t))
		} else if dur, _ := cmd.Flags().GetDuration("past"); dur > 0 {
			reqArgs = append(reqArgs, metar.HoursBeforeNow(dur.Hours()))
		}

		if mostRecent {
			reqArgs = append(reqArgs, metar.MostRecent(true))
		} else if mostRecentByStation != "" {
			reqArgs = append(reqArgs, metar.MostRecentForEachStation(mostRecentByStation))
		}

		if !rect.IsZero() {
			reqArgs = append(reqArgs, metar.LonLatRect(rect.minLat, rect.minLon, rect.maxLat, rect.maxLon))
		}

		if !radial.IsZero() {
			reqArgs = append(reqArgs, metar.RadialDistance(radial.radius, radial.lat, radial.lon))
		}

		if pathDist > 0 && len(waypoints) > 0 {
			reqArgs = append(reqArgs, metar.FlightPath(pathDist, waypoints...))
		}

		if minDist > 0 {
			reqArgs = append(reqArgs, metar.MinDegreeDistance(minDist))
		}

		var mc metar.Client
		res, err := mc.GetMETARs(context.Background(), metar.NewRequest(reqArgs...))
		if err != nil {
			fmt.Fprintf(os.Stderr, "could not get metar: %v\n", err)
			os.Exit(1)
		}
		if len(res.Errors) > 0 {
			for _, err := range res.Errors {
				fmt.Fprintf(os.Stderr, "error: %s\n", err)
			}
			os.Exit(2)
		}
		for _, m := range res.Data.METARs {
			fmt.Printf("%s\n", strings.TrimSpace(m.RawText))
		}
	},
}