package rgb

import (
	"fmt"
	"strings"

	"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"

// Effect is one named effect on a channel: the ID the keyboard uses and the name
// a definition gives it. The pair is explicit because a VIA definition may attach
// a number to an option that is not its position in the list, so a board's effect
// ID is not an index into its names.
type Effect struct {
	ID   uint8
	Name string
}

// 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.
//
// There is no compiled-in catalog for any board. A board's effect names come from
// its VIA definition file, read at runtime from the data directory or from the file
// --definition names, because a hand-written list and the vendor's file describing
// the same board are two places to update one name, and that is how they drift
// apart. A board with no definition has no names and is driven through raw effect
// IDs.
type Catalog struct {
	board   string
	names   map[via.Channel][]Effect
	aliases map[via.Channel]map[string]string
}

// NewCatalog returns a catalog for a board described by effect entries, as a VIA
// definition file provides them. The board name is what the effect list reports;
// the entries may leave gaps, because a definition names only the effects a board's
// firmware implements.
//
// The tool's aliases come with it, because they are a spelling convenience and not
// board knowledge: a definition writes the manufacturer's spelling, and the user
// should not have to know which one it chose.
func NewCatalog(board string, effects map[via.Channel][]Effect) *Catalog {
	return &Catalog{board: board, names: effects, aliases: defaultAliases}
}

// defaultAliases are the spellings every catalog accepts, whatever the source of
// its names. They resolve per channel, so `rainbow` is the vendor's `spectrum`
// where that is the name and the catalog's own on another channel.
var defaultAliases = 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",
	},
}

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

// Effects returns a channel's named effects, or nil when the catalog says nothing
// about it.
func (c *Catalog) Effects(ch via.Channel) []Effect {
	if c == nil {
		return nil
	}
	return c.names[ch]
}

// Names returns the effect names of a channel in effect-ID order, or nil when the
// catalog says nothing about it.
func (c *Catalog) Names(ch via.Channel) []string {
	effects := c.Effects(ch)
	if effects == nil {
		return nil
	}
	names := make([]string, 0, len(effects))
	for _, e := range effects {
		names = append(names, e.Name)
	}
	return names
}

// EffectName returns the name of an effect ID, or "unknown" when the catalog has no
// entry for it. A board may take an effect ID that no definition names, and then
// this says so rather than inventing a label for it.
func (c *Catalog) EffectName(ch via.Channel, id uint8) string {
	if c == nil {
		return unknownEffectName
	}
	for _, e := range c.names[ch] {
		if e.ID == id {
			return e.Name
		}
	}
	return unknownEffectName
}

// 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
	}
	if id, found := c.byName(ch, name); found {
		return id, true
	}
	if canonical, ok := c.aliases[ch][name]; ok {
		if id, found := c.EffectID(ch, canonical); found {
			return id, true
		}
	}
	// A definition may carry the other spelling of the same pair: the tool's alias
	// table says "breathe" for "breathing", and a manufacturer's file may use
	// either. So a name that is the target of an alias resolves to that alias where
	// the channel has it.
	for alias, canonical := range c.aliases[ch] {
		if canonical != name {
			continue
		}
		if id, found := c.byName(ch, alias); found {
			return id, true
		}
	}
	return 0, false
}

// byName finds an effect by its exact name, without following an alias, then by the
// same name with spaces written as underscores. A definition carries display
// spellings where the tool carries identifiers, and the difference is whitespace,
// not a different effect: "fixed wave" and "fixed_wave" name the same thing, and the
// tool's documented spelling has to keep working while a definition file is present.
func (c *Catalog) byName(ch via.Channel, name string) (uint8, bool) {
	for _, e := range c.names[ch] {
		if e.Name == name {
			return e.ID, true
		}
	}
	spaced := strings.ReplaceAll(name, "_", " ")
	if spaced != name {
		for _, e := range c.names[ch] {
			if e.Name == spaced {
				return e.ID, true
			}
		}
	}
	return 0, false
}

// DefaultEffect returns the effect enable writes when turning a channel on: the
// first effect the board's own list names that is not the off entry, which is what
// makes a channel light at all. A definition carries no notion of a default effect,
// so the board's list is where the answer comes from, and a channel whose list holds
// nothing but the off entry has none to give.
func (c *Catalog) DefaultEffect(ch via.Channel) (uint8, bool) {
	if c == nil {
		return 0, false
	}
	for _, e := range c.names[ch] {
		if e.ID != 0 {
			return e.ID, true
		}
	}
	return 0, false
}

// 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 {
		// Both ways out belong in the message: the board is still drivable by
		// number, and the names are one command away. A user who reads only the
		// error should not have to find either out elsewhere.
		return nil, nil, fmt.Errorf("no effect names for this keyboard: run `keyboard fetch` for its VIA definition, " +
			"or set an effect by number with `effect <index>`")
	}

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

	// Whether the board has the name at all is a different question from whether the
	// channels asked for can do it: naming a real effect on the wrong channel is a
	// different mistake, with a different fix, and gets its own message.
	knownAnywhere := false
	for ch := range catalog.names {
		if _, ok := catalog.EffectID(ch, name); ok {
			knownAnywhere = true
			break
		}
	}
	if !knownAnywhere {
		// A name nobody wrote is either a typo or a number that belongs in the
		// other form, and pointing at it saves the user from guessing.
		return nil, nil, fmt.Errorf("unknown effect: %s (an effect ID from 0 to 255 is `effect <index>`)", 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
}