package main

// How a satellite station points its antenna.
//
// It does NOT configure a rotator. Every rotator interface OpsLog knows lives in
// Settings ▸ Rotator, once, and the satellite page only CHOOSES one of them.
// The two used to be separate: EasyComm and PstRotator were described inside the
// satellite settings while five other backends were described in the rotator
// list, so an operator with one mast described it twice — and could describe it
// differently the second time, which is a station that works on HF and not on a
// pass, for no reason anyone can see.
//
// What remains here is the adapter: turning whichever backend the operator
// picked into the three things a pass needs — point it, ask where it is, let go
// of it at the end.

import (
	"fmt"
	"math"
	"strings"
	"sync"

	"hamlog/internal/rotator/gs232"
	"hamlog/internal/rotator/pst"
	"hamlog/internal/rotator/spid"
)

// satRotator is what the tracker needs of an antenna: point it, ask where it
// is, and let go of it at the end of the pass.
type satRotator interface {
	Point(az, el float64) error
	// Heading reports where the antenna is. live is false when the answer is
	// the last commanded position rather than a reading — a stuck rotator must
	// not be able to hide behind an order it never carried out.
	Heading() (az, el float64, live bool, err error)
	Close()
}

// The legacy satellite-only rotator kinds. They are no longer stored; they
// survive only so migrateSatRotator can read what an operator configured before
// the rotator list existed.
const (
	satRotEasycomm = "easycomm"
	satRotPst      = "pstrotator"
)

// newSatRotator builds a controller for the rotor the satellite page selected.
func (a *App) newSatRotator(s SatSettings) (satRotator, error) {
	if strings.TrimSpace(s.RotID) == "" {
		return nil, fmt.Errorf("no rotator chosen for satellite tracking — pick one in Settings ▸ Satellite")
	}
	lr, ok := a.rotorByKey(s.RotID)
	if !ok {
		// The rotor was deleted from the list after being chosen here. Say that,
		// rather than failing to connect to an address nobody can see any more.
		return nil, fmt.Errorf("the rotator chosen for satellite tracking no longer exists in Settings ▸ Rotator")
	}
	// Azimuth only: any rotor will do, including the tower the operator already
	// turns for HF. See SatSettings.RotAzOnly for why this is the common case
	// rather than a fallback.
	if s.RotAzOnly {
		return &azOnlySatRotator{link: lr.Link}, nil
	}
	if !lr.HasEl {
		name := strings.TrimSpace(lr.Name)
		if name == "" {
			name = "this rotator"
		}
		return nil, fmt.Errorf("%s has no elevation axis — tick \"follow the azimuth only\" in Settings ▸ Satellite, or pick an az/el rotator", name)
	}
	l := lr.Link
	switch l.Type {
	case "pst":
		return &pstSatRotator{c: pst.New(l.Host, l.Port), maxAz: l.MaxAz}, nil
	case "easycomm":
		return easycommClient(l), nil
	case "erc":
		return &gs232SatRotator{c: ercClient(l), maxAz: l.MaxAz}, nil
	case "spid":
		return &spidSatRotator{c: spidClient(l)}, nil
	default:
		return nil, fmt.Errorf("the %s backend cannot be pointed in elevation", l.Type)
	}
}

// SatelliteRotorChoice is one entry in the satellite page's rotator dropdown.
type SatelliteRotorChoice struct {
	Key string `json:"key"`
	// Name is the operator's label; Type is the backend's, for the rotors left
	// unnamed (a list of three blank rows is a list of one rotor as far as
	// anybody can tell).
	Name  string `json:"name"`
	Type  string `json:"type"`
	HasEl bool   `json:"has_el"`
}

// ListSatelliteRotors returns every configured rotor, elevation-capable or not.
//
// Never filtered. Which of them can be USED depends on the azimuth-only switch,
// and that is a question for the panel: with it off an azimuth rotor is shown
// greyed and says why, with it on every rotor is fair game. Hiding them
// outright would only teach an operator with one mast that OpsLog cannot find
// it.
func (a *App) ListSatelliteRotors() ([]SatelliteRotorChoice, error) {
	devs, err := a.GetRotators()
	if err != nil {
		return nil, err
	}
	out := []SatelliteRotorChoice{}
	for _, r := range flattenRotors(devs) {
		out = append(out, SatelliteRotorChoice{
			Key: r.Key, Name: r.Name, Type: rotorTypeInfo(r.Link.Type).Label, HasEl: r.HasEl,
		})
	}
	return out, nil
}

// gs232SatRotator points an ERC-M (or any GS-232 az/el controller) through the
// W command.
//
// The 450° overlap is handled HERE and not in the package, the same way the
// EasyComm client does it: a controller reports 0-450 and takes 0-450, but the
// tracker works in true bearings, and which of the two ways round to reach 010°
// depends on where the mast currently is.
type gs232SatRotator struct {
	c     *gs232.Client
	maxAz int
}

func (g *gs232SatRotator) Point(az, el float64) error {
	return g.c.GoToAzEl(int(math.Round(satWrapAz(az, g.maxAz))), int(math.Round(clampEl(el))))
}

func (g *gs232SatRotator) Heading() (float64, float64, bool, error) {
	az, el, _, err := g.c.Position()
	if err != nil {
		return 0, 0, false, err
	}
	return float64(az), float64(el), true, nil
}

// Close: nothing to release. The serial port is held by the gs232 package, which
// keeps it open across the whole session on purpose — an Arduino-based
// controller reboots every time its port is opened.
func (g *gs232SatRotator) Close() {}

// spidSatRotator points a SPID Rot2Prog. Its protocol is absolute and binary,
// with no overlap notion to manage: the controller is told a bearing and a
// resolution and works out its own path.
type spidSatRotator struct{ c *spid.Client }

func (s *spidSatRotator) Point(az, el float64) error {
	a := math.Mod(az, 360)
	if a < 0 {
		a += 360
	}
	return s.c.GoTo(int(math.Round(a)), int(math.Round(clampEl(el))))
}

func (s *spidSatRotator) Heading() (float64, float64, bool, error) {
	az, el, err := s.c.Heading()
	if err != nil {
		return 0, 0, false, err
	}
	return float64(az), float64(el), true, nil
}

func (s *spidSatRotator) Close() {}

// satWrapAz maps a true bearing onto what the controller accepts. On a 450°
// mast the far end of the overlap is reachable two ways and the higher number is
// chosen for the last 90°, which is what keeps a pass crossing north from
// unwinding the cable in the middle of it.
func satWrapAz(az float64, maxAz int) float64 {
	a := math.Mod(az, 360)
	if a < 0 {
		a += 360
	}
	if maxAz == 450 && a < 90 {
		return a + 360
	}
	return a
}

// clampEl keeps the elevation inside what a mast will accept. 180 and not 90: a
// G-5500 goes past the zenith and keeps counting, which is how an overhead pass
// is followed without swinging the azimuth 180° through the middle of it.
func clampEl(el float64) float64 {
	if el < 0 {
		return 0
	}
	if el > 180 {
		return 180
	}
	return el
}

// pstSatRotator points the antenna through PstRotator.
//
// PstRotator takes whole degrees and does its own overlap handling for a 450°
// rotator — it knows which controller is on the other end, and OpsLog does not.
// So the azimuth is sent plainly, and the 450° logic that the direct backends
// need is deliberately NOT applied here: two programs each deciding to go the
// long way round is how an antenna ends up unwinding in the middle of a pass.
type pstSatRotator struct {
	c     *pst.Client
	maxAz int

	mu sync.Mutex
	// lastAz/lastEl are what was commanded, for the display when PstRotator
	// does not answer a position query — which is the usual case for the many
	// setups whose controller reports nothing back to it either.
	lastAz, lastEl float64
	commanded      bool
	azSilent       bool // the azimuth query went unanswered; stop asking
	elSilent       bool // likewise for elevation, and far more common
}

func (p *pstSatRotator) Point(az, el float64) error {
	a := math.Mod(az, 360)
	if a < 0 {
		a += 360
	}
	el = clampEl(el)
	if err := p.c.GoTo(int(math.Round(a)), true, int(math.Round(el))); err != nil {
		return err
	}
	p.mu.Lock()
	p.lastAz, p.lastEl, p.commanded = a, el, true
	p.mu.Unlock()
	return nil
}

func (p *pstSatRotator) Heading() (float64, float64, bool, error) {
	p.mu.Lock()
	azSilent, elSilent, la, le, commanded := p.azSilent, p.elSilent, p.lastAz, p.lastEl, p.commanded
	p.mu.Unlock()

	az, el, live := la, le, false
	if !azSilent {
		if v, _, err := p.c.Heading(); err == nil {
			az, live = float64(v), true
		} else {
			// One silence is enough. Each query binds a socket and waits a second
			// and a half; repeating that every few seconds for a setup that will
			// never answer is a stall per poll for nothing.
			p.mu.Lock()
			p.azSilent = true
			p.mu.Unlock()
		}
	}
	if !elSilent {
		if v, _, err := p.c.Elevation(); err == nil {
			el = float64(v)
		} else {
			p.mu.Lock()
			p.elSilent = true
			p.mu.Unlock()
		}
	}
	if !live && !commanded {
		return 0, 0, false, fmt.Errorf("PstRotator does not report the antenna position")
	}
	return az, el, live, nil
}

// Close: nothing to release. Every PstRotator command is one datagram, and the
// socket lives for the length of a single write.
func (p *pstSatRotator) Close() {}

// azOnlySatRotator follows the satellite in azimuth and never touches the
// elevation axis, whatever the rotor happens to have.
//
// It works because of the geometry, not in spite of it: a pass at the far edge
// of the footprint stays between the horizon and about fifteen degrees for its
// whole length, and a yagi's beamwidth swallows that. What it costs is the high
// passes — a bird straight overhead is a moving azimuth and a useless bearing —
// and that is the operator's trade to make, which is why it is a switch and not
// a silent fallback.
//
// It drives whichever rotor was chosen through the same per-backend dispatch the
// compass uses, so a PstRotator, a Rotator Genius, an ARCO, a DCU-1, a SPID and
// the az/el ones all work here without a second implementation of each.
type azOnlySatRotator struct{ link rotorLink }

// Point sends the azimuth alone. The elevation is passed as -1, the callers'
// "no opinion", so a rotor that HAS an elevation axis is left where it is rather
// than being driven to the horizon.
func (r *azOnlySatRotator) Point(az, _ float64) error {
	a := math.Mod(az, 360)
	if a < 0 {
		a += 360
	}
	return linkGoTo(r.link, int(math.Round(a)), -1)
}

// Heading reports the azimuth. The elevation comes back as whatever the
// controller said, which for an azimuth rotor is zero — the panel is told
// separately not to draw it (SatTrackStatus.RotAzOnly), because zero is a real
// bearing and not the absence of one.
//
// live stays true when the AZIMUTH was genuinely read: it means "this is a
// reading and not the last command", and that answer is honest whatever the
// other axis does or does not do.
func (r *azOnlySatRotator) Heading() (float64, float64, bool, error) {
	az, el, _, _, err := linkHeading(r.link)
	if err != nil {
		return 0, 0, false, err
	}
	return az, el, true, nil
}

func (r *azOnlySatRotator) Close() {}