Initial commit

2026-08-08 11:04:45 +02:00
commit 4137962252
10 changed files with 1322 additions and 0 deletions
@@ -0,0 +1,200 @@
+package state
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"sync"
+	"time"
+)
+
+const PaletteSize = 16
+
+type Row []uint8
+
+func (r Row) MarshalJSON() ([]byte, error) {
+	vals := make([]int, len(r))
+	for i, v := range r {
+		vals[i] = int(v)
+	}
+	return json.Marshal(vals)
+}
+
+func (r *Row) UnmarshalJSON(data []byte) error {
+	var vals []int
+	if err := json.Unmarshal(data, &vals); err != nil {
+		return err
+	}
+	row := make(Row, len(vals))
+	for i, v := range vals {
+		if v < 0 || v > 255 {
+			return fmt.Errorf("pixel value %d out of range", v)
+		}
+		row[i] = uint8(v)
+	}
+	*r = row
+	return nil
+}
+
+var (
+	ErrOutOfBounds  = errors.New("coordinates out of bounds")
+	ErrInvalidColor = errors.New("invalid color index")
+	ErrImageTooBig  = errors.New("image too large")
+	ErrEmptyMessage = errors.New("message is empty")
+	ErrMessageLong  = errors.New("message too long")
+)
+
+type Message struct {
+	Text string    `json:"text"`
+	At   time.Time `json:"at"`
+}
+
+type State struct {
+	mu          sync.RWMutex
+	Width       int       `json:"width"`
+	Height      int       `json:"height"`
+	Pixels      []Row `json:"pixels"`
+	Messages    []Message `json:"messages"`
+	maxMessages int
+	maxMsgLen   int
+	maxImageDim int
+}
+
+func New(width, height int) *State {
+	pixels := make([]Row, height)
+	for i := range pixels {
+		pixels[i] = make(Row, width)
+	}
+	return &State{
+		Width:       width,
+		Height:      height,
+		Pixels:      pixels,
+		Messages:    []Message{},
+		maxMessages: 50,
+		maxMsgLen:   140,
+		maxImageDim: 32,
+	}
+}
+
+func (s *State) CheckPixel(x, y int, color uint8) error {
+	if x < 0 || x >= s.Width || y < 0 || y >= s.Height {
+		return ErrOutOfBounds
+	}
+	if color >= PaletteSize {
+		return ErrInvalidColor
+	}
+	return nil
+}
+
+func (s *State) SetPixel(x, y int, color uint8) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if err := s.CheckPixel(x, y, color); err != nil {
+		return err
+	}
+	s.Pixels[y][x] = color
+	return nil
+}
+
+func (s *State) StampImage(x, y int, pixels []Row) error {
+	if len(pixels) == 0 || len(pixels) > s.maxImageDim {
+		return ErrImageTooBig
+	}
+	for _, row := range pixels {
+		if len(row) == 0 || len(row) > s.maxImageDim {
+			return ErrImageTooBig
+		}
+		for _, c := range row {
+			if c >= PaletteSize {
+				return ErrInvalidColor
+			}
+		}
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	for dy, row := range pixels {
+		for dx, c := range row {
+			px, py := x+dx, y+dy
+			if px >= 0 && px < s.Width && py >= 0 && py < s.Height {
+				s.Pixels[py][px] = c
+			}
+		}
+	}
+	return nil
+}
+
+func (s *State) AddMessage(text string) error {
+	if text == "" {
+		return ErrEmptyMessage
+	}
+	if len(text) > s.maxMsgLen {
+		return ErrMessageLong
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.Messages = append(s.Messages, Message{Text: text, At: time.Now().UTC()})
+	if len(s.Messages) > s.maxMessages {
+		s.Messages = s.Messages[len(s.Messages)-s.maxMessages:]
+	}
+	return nil
+}
+
+type Snapshot struct {
+	Width    int       `json:"width"`
+	Height   int       `json:"height"`
+	Pixels   []Row `json:"pixels"`
+	Messages []Message `json:"messages"`
+}
+
+func (s *State) Snapshot() Snapshot {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	pixels := make([]Row, s.Height)
+	for i, row := range s.Pixels {
+		cp := make(Row, len(row))
+		copy(cp, row)
+		pixels[i] = cp
+	}
+	msgs := make([]Message, len(s.Messages))
+	copy(msgs, s.Messages)
+	return Snapshot{Width: s.Width, Height: s.Height, Pixels: pixels, Messages: msgs}
+}
+
+func (s *State) Save(path string) error {
+	snap := s.Snapshot()
+	data, err := json.Marshal(snap)
+	if err != nil {
+		return err
+	}
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, data, 0o644); err != nil {
+		return err
+	}
+	return os.Rename(tmp, path)
+}
+
+func Load(path string) (*State, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	var snap Snapshot
+	if err := json.Unmarshal(data, &snap); err != nil {
+		return nil, err
+	}
+	if snap.Width <= 0 || snap.Height <= 0 || len(snap.Pixels) != snap.Height {
+		return nil, fmt.Errorf("invalid snapshot dimensions")
+	}
+	for _, row := range snap.Pixels {
+		if len(row) != snap.Width {
+			return nil, fmt.Errorf("invalid snapshot row width")
+		}
+	}
+	st := New(snap.Width, snap.Height)
+	st.Pixels = snap.Pixels
+	if snap.Messages != nil {
+		st.Messages = snap.Messages
+	}
+	return st, nil
+}