// Package app is the Wails service the frontend calls. It owns the current
// project and returns a fresh State after every call; the frontend keeps no
// project data of its own (build plan 4.6 and 5).
package app

import (
	"fmt"
	"sync"

	"git.monoexp.com/bajdev/mpckit/internal/project"
)

// Version is set at build time with
// -ldflags "-X git.monoexp.com/bajdev/mpckit/internal/app.Version=v1.0.0".
var Version = "dev"

// DefaultName is the name of a new project.
const DefaultName = "NewKit"

// Pad is one pad as the frontend shows it.
type Pad struct {
	Slot      int    `json:"slot"`
	Label     string `json:"label"` // "A01" .. "H16"
	Name      string `json:"name"`  // sample name; empty for an empty pad
	File      string `json:"file"`  // pool file name
	Coarse    int    `json:"coarse"`
	Fine      int    `json:"fine"`
	MuteGroup int    `json:"muteGroup"`
	HasNotes  bool   `json:"hasNotes"`
}

// Sequence is one existing sequence.
type Sequence struct {
	Slot     int     `json:"slot"`
	Label    string  `json:"label"` // slot label, "A01" .. "H16"
	Name     string  `json:"name"`
	BPM      float64 `json:"bpm"`
	Bars     int     `json:"bars"`
	HasNotes bool    `json:"hasNotes"`
}

// Limits are the ranges the UI offers, from the device checks.
type Limits struct {
	Pads         int     `json:"pads"`
	MaxSamples   int     `json:"maxSamples"`
	MaxSequences int     `json:"maxSequences"`
	MinCoarse    int     `json:"minCoarse"`
	MaxCoarse    int     `json:"maxCoarse"`
	MinFine      int     `json:"minFine"`
	MaxFine      int     `json:"maxFine"`
	MaxMuteGroup int     `json:"maxMuteGroup"`
	MinBPM       float64 `json:"minBPM"`
	MaxBPM       float64 `json:"maxBPM"`
	MaxBars      int     `json:"maxBars"`
}

// State is everything the frontend shows about the project.
type State struct {
	Name          string     `json:"name"`
	Dirty         bool       `json:"dirty"`
	Pads          []Pad      `json:"pads"`      // all 128, in slot order
	Sequences     []Sequence `json:"sequences"` // existing ones, in slot order
	SampleCount   int        `json:"sampleCount"`
	SequenceCount int        `json:"sequenceCount"`
	Limits        Limits     `json:"limits"`
}

// About is the text for the About dialog.
type About struct {
	Version string `json:"version"`
	License string `json:"license"`
	Repo    string `json:"repo"`
}

// Service is registered with Wails; its exported methods become the
// frontend bindings.
type Service struct {
	mu sync.Mutex
	p  *project.Project
}

// NewService returns a service holding a new, empty project.
func NewService() *Service {
	s := &Service{}
	s.reset()
	return s
}

func (s *Service) reset() {
	p, err := project.New(DefaultName)
	if err != nil {
		panic(err) // the embedded template and a constant name
	}
	s.p = p
}

// New replaces the current project with a new, empty one.
func (s *Service) New() State {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.reset()
	return s.state()
}

// State returns the current project's state.
func (s *Service) State() State {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.state()
}

// Version returns the app version.
func (s *Service) Version() string { return Version }

// About returns the About dialog text.
func (s *Service) About() About {
	return About{
		Version: Version,
		License: "MIT License, copyright (c) 2026 bajdev",
		Repo:    "https://git.monoexp.com/bajdev/mpckit",
	}
}

// Label returns the label the UI and the device use for a pad or sequence
// slot: bank letter and two-digit pad number, e.g. 0 -> "A01", 17 -> "B02".
func Label(slot int) string {
	return fmt.Sprintf("%c%02d", 'A'+slot/16, slot%16+1)
}

func (s *Service) state() State {
	p := s.p
	st := State{
		Name:        p.Name,
		Dirty:       p.Dirty,
		Pads:        make([]Pad, 0, project.Pads),
		Sequences:   []Sequence{},
		SampleCount: p.SampleCount(),
		Limits: Limits{
			Pads:         project.Pads,
			MaxSamples:   project.MaxSamples,
			MaxSequences: project.MaxSequences,
			MinCoarse:    project.MinCoarse,
			MaxCoarse:    project.MaxCoarse,
			MinFine:      project.MinFine,
			MaxFine:      project.MaxFine,
			MaxMuteGroup: project.MaxMuteGroup,
			MinBPM:       project.MinBPM,
			MaxBPM:       project.MaxBPM,
			MaxBars:      project.MaxBars,
		},
	}
	for slot := 0; slot < project.Pads; slot++ {
		v, err := p.Pad(slot)
		if err != nil {
			// A loaded file with an odd pad; show it as empty.
			st.Pads = append(st.Pads, Pad{Slot: slot, Label: Label(slot)})
			continue
		}
		pad := Pad{Slot: slot, Label: Label(slot), Name: v.SampleName, File: v.File,
			Coarse: v.Coarse, Fine: v.Fine, MuteGroup: v.MuteGroup}
		if !v.Empty() {
			pad.HasNotes = p.PadHasNotes(slot)
		}
		st.Pads = append(st.Pads, pad)
	}
	for _, q := range p.Sequences() {
		st.Sequences = append(st.Sequences, Sequence{Slot: q.Slot, Label: Label(q.Slot),
			Name: q.Name, BPM: q.BPM, Bars: q.Bars, HasNotes: q.HasNotes})
	}
	st.SequenceCount = len(st.Sequences)
	return st
}