package rgb

import (
	"fmt"

	"netdome.biz/paul/qmk-rgb/internal/via"
)

// EffectTarget is one effect ID to write to one channel.
type EffectTarget struct {
	Channel via.Channel
	ID      uint8
}

const unknownEffectName = "unknown"

// Catalog is one board's effect names, per channel. The keyboard holds numbers,
// not names, so `effect <name>` needs a catalog and a board without one is
// driven through raw IDs.
type Catalog struct {
	board    string
	names    map[via.Channel][]string
	aliases  map[via.Channel]map[string]string
	defaults map[via.Channel]uint8
}

// CatalogFor returns the effect catalog of a board, and whether one exists.
//
// Provenance, because these lists look invented and are not:
//
//   - The 46 backlight names are QMK's rgb_matrix_effects.inc in order, each ID
//     verified against the live register of an Impact 80.
//   - The 7 logo and 7 side names are this board's vendor VIA definition, whose
//     dropdowns read "fixed wave" and "breathe". The tool spells them
//     fixed_wave and breathing and accepts the vendor's spellings as aliases.
//   - The brightness and speed transforms documented in README.md were measured
//     on the unit, not read from anywhere.
func CatalogFor(vendorID, productID uint16) (*Catalog, bool) {
	if vendorID != 0x36B0 || productID != 0x309F {
		return nil, false
	}
	return &Catalog{
		board: "impact80",
		names: map[via.Channel][]string{
			via.ChannelRgblight:  impact80LogoEffects[:],
			via.ChannelRgbMatrix: impact80BacklightEffects[:],
			via.ChannelAudio:     impact80SideEffects[:],
		},
		aliases: map[via.Channel]map[string]string{
			via.ChannelRgblight: {
				"off":          "none",
				"breathe":      "breathing",
				"rainbow":      "spectrum",
				"rainbow_wave": "wave",
				"solid":        "light",
				"static":       "solid",
			},
			via.ChannelRgbMatrix: {
				"off":     "none",
				"breathe": "breathing",
				"rainbow": "rainbow_moving_chevron",
				"solid":   "solid_color",
				"static":  "solid",
			},
			via.ChannelAudio: {
				"off":          "none",
				"breathe":      "breathing",
				"rainbow":      "spectrum",
				"rainbow_wave": "wave",
				"solid":        "light",
				"static":       "solid",
			},
		},
		defaults: map[via.Channel]uint8{
			via.ChannelRgblight:  4,
			via.ChannelRgbMatrix: 5,
			via.ChannelAudio:     4,
		},
	}, true
}

// Name returns the catalog's board name, which `effect --list` reports.
func (c *Catalog) Name() string {
	if c == nil {
		return ""
	}
	return c.board
}

// Names returns the effect names of a channel, or nil when the catalog says
// nothing about it.
func (c *Catalog) Names(ch via.Channel) []string {
	if c == nil {
		return nil
	}
	return c.names[ch]
}

// EffectName returns the name of an effect ID, or "unknown" when the catalog has
// no entry for it.
func (c *Catalog) EffectName(ch via.Channel, id uint8) string {
	if c == nil {
		return unknownEffectName
	}
	names := c.names[ch]
	if int(id) >= len(names) {
		return unknownEffectName
	}
	return names[id]
}

// EffectID resolves an effect name on a channel, following one level of alias.
func (c *Catalog) EffectID(ch via.Channel, name string) (uint8, bool) {
	if c == nil {
		return 0, false
	}
	for id, candidate := range c.names[ch] {
		if candidate == name {
			return uint8(id), true
		}
	}
	if canonical, ok := c.aliases[ch][name]; ok {
		for id, candidate := range c.names[ch] {
			if candidate == canonical {
				return uint8(id), true
			}
		}
	}
	return 0, false
}

// DefaultEffect returns the effect ID enable writes when turning a channel on.
func (c *Catalog) DefaultEffect(ch via.Channel) (uint8, bool) {
	if c == nil {
		return 0, false
	}
	id, ok := c.defaults[ch]
	return id, ok
}

// ResolveEffect turns an effect name into one target per channel that supports
// it, plus the subsystem names of those that do not. A skip is an error rather
// than a warning when the caller asked for one channel explicitly, because a
// command that silently did nothing looks like a command that worked. That is
// the caller's knowledge to pass: a board with a single lighting channel is not
// an explicit request for it.
func ResolveEffect(catalog *Catalog, name string, channels []via.Channel, explicit bool) ([]EffectTarget, []string, error) {
	if catalog == nil {
		return nil, nil, fmt.Errorf("no effect catalog for this keyboard; set an effect by number with `mode <index>`")
	}

	// The compatibility spelling every catalog shares, so a caller cannot
	// resolve "static" differently from another.
	if name == "static" {
		name = "solid"
	}

	known := false
	for _, ch := range channels {
		if _, ok := catalog.EffectID(ch, name); ok {
			known = true
			break
		}
	}
	if !known {
		return nil, nil, fmt.Errorf("unknown effect: %s", name)
	}

	var targets []EffectTarget
	var skipped []string

	for _, ch := range channels {
		id, ok := catalog.EffectID(ch, name)
		if !ok {
			if explicit {
				return nil, nil, fmt.Errorf("effect %s is not supported on %s", name, ch.Subsystem())
			}
			skipped = append(skipped, ch.Subsystem())
			continue
		}
		targets = append(targets, EffectTarget{Channel: ch, ID: id})
	}
	return targets, skipped, nil
}