grindlemire/go-tui code browser

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438

package tui

import (
	"fmt"
	"strconv"
	"strings"
)

// EmulatorTerminal is a terminal emulator for testing that processes ANSI escape
// sequences and maintains both a visible screen and scrollback buffer.
// This allows tests to verify what SetInlineHeight, PrintAboveln, and other
// inline mode operations actually do to the terminal.
type EmulatorTerminal struct {
	width, height int
	screen        [][]rune // visible screen: screen[row][col]
	scrollback    []string // lines that scrolled off the top
	cursorRow     int      // 0-indexed
	cursorCol     int      // 0-indexed
	cursorHidden  bool
	inRawMode     bool
	inAltScreen   bool
	mouseEnabled  bool
	altScroll     bool
	caps          Capabilities

	// Scroll region (0-indexed, inclusive). Defaults to full screen.
	scrollTop    int // top row of scroll region
	scrollBottom int // bottom row of scroll region
}

var _ Terminal = (*EmulatorTerminal)(nil)

// NewEmulatorTerminal creates a terminal emulator with the given dimensions.
// The screen is initialized with spaces.
func NewEmulatorTerminal(width, height int) *EmulatorTerminal {
	screen := make([][]rune, height)
	for i := range screen {
		screen[i] = make([]rune, width)
		for j := range screen[i] {
			screen[i][j] = ' '
		}
	}
	return &EmulatorTerminal{
		width:        width,
		height:       height,
		screen:       screen,
		scrollTop:    0,
		scrollBottom: height - 1,
		caps: Capabilities{
			Colors:    Color256,
			Unicode:   true,
			TrueColor: true,
			AltScreen: true,
		},
	}
}

func (e *EmulatorTerminal) Size() (int, int)             { return e.width, e.height }
func (e *EmulatorTerminal) Caps() Capabilities           { return e.caps }
func (e *EmulatorTerminal) EnterRawMode() error          { e.inRawMode = true; return nil }
func (e *EmulatorTerminal) ExitRawMode() error           { e.inRawMode = false; return nil }
func (e *EmulatorTerminal) EnterAltScreen()              { e.inAltScreen = true }
func (e *EmulatorTerminal) ExitAltScreen()               { e.inAltScreen = false }
func (e *EmulatorTerminal) EnableMouse()                 { e.mouseEnabled = true }
func (e *EmulatorTerminal) DisableMouse()                { e.mouseEnabled = false }
func (e *EmulatorTerminal) EnableAltScroll()             { e.altScroll = true }
func (e *EmulatorTerminal) DisableAltScroll()            { e.altScroll = false }
func (e *EmulatorTerminal) NegotiateKittyKeyboard() bool { return false }
func (e *EmulatorTerminal) EnableKittyKeyboard()         {}
func (e *EmulatorTerminal) DisableKittyKeyboard()        {}
func (e *EmulatorTerminal) ResetStyle()                  {}
func (e *EmulatorTerminal) HideCursor()                  { e.cursorHidden = true }
func (e *EmulatorTerminal) ShowCursor()                  { e.cursorHidden = false }
func (e *EmulatorTerminal) SetCursor(x, y int)           { e.cursorCol = x; e.cursorRow = y }

func (e *EmulatorTerminal) Clear() {
	for r := 0; r < e.height; r++ {
		for c := 0; c < e.width; c++ {
			e.screen[r][c] = ' '
		}
	}
	e.cursorRow = 0
	e.cursorCol = 0
}

func (e *EmulatorTerminal) ClearToEnd() {
	// Clear from cursor to end of screen
	for c := e.cursorCol; c < e.width; c++ {
		e.screen[e.cursorRow][c] = ' '
	}
	for r := e.cursorRow + 1; r < e.height; r++ {
		for c := 0; c < e.width; c++ {
			e.screen[r][c] = ' '
		}
	}
}

func (e *EmulatorTerminal) Flush(changes []CellChange) {
	for _, ch := range changes {
		if ch.Y < 0 || ch.Y >= e.height {
			continue
		}
		if ch.EraseToEOL {
			for x := ch.X; x < e.width; x++ {
				if x >= 0 {
					e.screen[ch.Y][x] = ' '
				}
			}
			continue
		}
		if ch.X >= 0 && ch.X < e.width {
			r := ch.Cell.Rune
			if r == 0 {
				r = ' '
			}
			e.screen[ch.Y][ch.X] = r
		}
	}
}

// WriteDirect processes raw bytes containing ANSI escape sequences.
// This is the key method that makes EmulatorTerminal useful for testing —
// it actually interprets the escape sequences instead of discarding them.
func (e *EmulatorTerminal) WriteDirect(b []byte) (int, error) {
	s := string(b)
	i := 0
	for i < len(s) {
		if s[i] == '\033' {
			// ESC sequence
			if i+1 < len(s) {
				switch s[i+1] {
				case '[':
					// CSI sequence
					consumed := e.parseCSI(s[i+2:])
					i += 2 + consumed
				case 'M':
					// Reverse Index
					e.reverseIndex()
					i += 2
				default:
					i += 2
				}
			} else {
				i++
			}
		} else if s[i] == '\n' {
			e.linefeed()
			i++
		} else if s[i] == '\r' {
			e.cursorCol = 0
			i++
		} else {
			// Printable character
			if e.cursorRow >= 0 && e.cursorRow < e.height &&
				e.cursorCol >= 0 && e.cursorCol < e.width {
				e.screen[e.cursorRow][e.cursorCol] = rune(s[i])
				e.cursorCol++
			}
			i++
		}
	}
	return len(b), nil
}

// parseCSI parses a CSI (Control Sequence Introducer) sequence starting after "\033[".
// Returns the number of bytes consumed from s.
func (e *EmulatorTerminal) parseCSI(s string) int {
	// Collect parameters and final character
	i := 0
	for i < len(s) {
		ch := s[i]
		if ch >= 0x40 && ch <= 0x7E {
			// Final character found
			params := s[:i]
			switch ch {
			case 'H': // CUP - Cursor Position
				e.cursorPosition(params)
			case 'r': // DECSTBM - Set Scrolling Region
				e.setScrollRegion(params)
			case 'K': // EL - Erase in Line
				e.eraseLine(params)
			case 'M': // DL - Delete Lines
				e.deleteLines(params)
			case 'J': // ED - Erase in Display
				e.eraseDisplay(params)
			}
			return i + 1
		}
		i++
	}
	return i
}

// cursorPosition handles ESC[row;colH (1-indexed)
func (e *EmulatorTerminal) cursorPosition(params string) {
	row, col := 1, 1
	if params != "" {
		parts := strings.Split(params, ";")
		if len(parts) >= 1 && parts[0] != "" {
			row, _ = strconv.Atoi(parts[0])
		}
		if len(parts) >= 2 && parts[1] != "" {
			col, _ = strconv.Atoi(parts[1])
		}
	}
	e.cursorRow = row - 1 // convert to 0-indexed
	e.cursorCol = col - 1
}

// setScrollRegion handles ESC[top;bottomr (1-indexed)
// Real terminals move cursor to home position (0,0) on any DECSTBM.
func (e *EmulatorTerminal) setScrollRegion(params string) {
	if params == "" {
		// Reset to full screen
		e.scrollTop = 0
		e.scrollBottom = e.height - 1
		e.cursorRow = 0
		e.cursorCol = 0
		return
	}
	parts := strings.Split(params, ";")
	top := 1
	bottom := e.height
	if len(parts) >= 1 && parts[0] != "" {
		top, _ = strconv.Atoi(parts[0])
	}
	if len(parts) >= 2 && parts[1] != "" {
		bottom, _ = strconv.Atoi(parts[1])
	}
	e.scrollTop = top - 1       // convert to 0-indexed
	e.scrollBottom = bottom - 1 // convert to 0-indexed
	e.cursorRow = 0
	e.cursorCol = 0
}

// eraseLine handles ESC[nK
func (e *EmulatorTerminal) eraseLine(params string) {
	n := 0
	if params != "" {
		n, _ = strconv.Atoi(params)
	}
	if e.cursorRow < 0 || e.cursorRow >= e.height {
		return
	}
	switch n {
	case 0: // clear from cursor to end of line
		for c := e.cursorCol; c < e.width; c++ {
			e.screen[e.cursorRow][c] = ' '
		}
	case 1: // clear from start of line to cursor
		for c := 0; c <= e.cursorCol && c < e.width; c++ {
			e.screen[e.cursorRow][c] = ' '
		}
	case 2: // clear entire line
		for c := 0; c < e.width; c++ {
			e.screen[e.cursorRow][c] = ' '
		}
	}
}

// deleteLines handles ESC[nM (Delete n lines at cursor, shift below up)
// Matches real terminal behavior: when the cursor is at the top of a scroll
// region that starts at row 0 (screen top), deleted lines are pushed to
// scrollback — the same as normal scrolling. When the scroll region starts
// below row 0, or the cursor is not at the top of the region, lines are discarded.
func (e *EmulatorTerminal) deleteLines(params string) {
	n := 1
	if params != "" {
		n, _ = strconv.Atoi(params)
	}
	for count := 0; count < n; count++ {
		if e.cursorRow <= e.scrollBottom {
			// Real terminal behavior: if scroll region starts at screen top
			// and cursor is at top of region, push deleted line to scrollback
			if e.scrollTop == 0 && e.cursorRow == 0 {
				line := strings.TrimRight(string(e.screen[0]), " ")
				e.scrollback = append(e.scrollback, line)
			}
			// Shift lines up
			for r := e.cursorRow; r < e.scrollBottom; r++ {
				copy(e.screen[r], e.screen[r+1])
			}
			// Blank the bottom line of scroll region
			for c := 0; c < e.width; c++ {
				e.screen[e.scrollBottom][c] = ' '
			}
		}
	}
}

// eraseDisplay handles ESC[nJ
func (e *EmulatorTerminal) eraseDisplay(params string) {
	n := 0
	if params != "" {
		n, _ = strconv.Atoi(params)
	}
	switch n {
	case 0: // clear from cursor to end of screen
		e.ClearToEnd()
	case 2: // clear entire screen
		e.Clear()
	}
}

// linefeed handles \n — if cursor is at the bottom of the scroll region,
// scrolls the region up (top line goes to scrollback). Otherwise moves cursor down.
func (e *EmulatorTerminal) linefeed() {
	if e.cursorRow == e.scrollBottom {
		// At bottom of scroll region: scroll up
		e.scrollRegionUp()
	} else if e.cursorRow < e.height-1 {
		e.cursorRow++
	}
}

// scrollRegionUp scrolls the scroll region up by one line.
// Matches real terminal behavior: the top line of the region goes to scrollback
// ONLY when the scroll region starts at the screen top (row 0). When the region
// starts below row 0, the top line is discarded.
func (e *EmulatorTerminal) scrollRegionUp() {
	// Real terminals only push to scrollback when scroll region starts at screen top
	line := strings.TrimRight(string(e.screen[e.scrollTop]), " ")
	if e.scrollTop == 0 {
		e.scrollback = append(e.scrollback, line)
	}

	// Shift lines up within the scroll region
	for r := e.scrollTop; r < e.scrollBottom; r++ {
		copy(e.screen[r], e.screen[r+1])
	}

	// Blank the bottom line of the region
	for c := 0; c < e.width; c++ {
		e.screen[e.scrollBottom][c] = ' '
	}
}

// reverseIndex handles ESC M — if cursor is at the top of the scroll region,
// scrolls the region down (bottom line falls off). Otherwise moves cursor up.
func (e *EmulatorTerminal) reverseIndex() {
	if e.cursorRow == e.scrollTop {
		// At top of scroll region: scroll down (insert blank at top, bottom falls off)
		for r := e.scrollBottom; r > e.scrollTop; r-- {
			copy(e.screen[r], e.screen[r-1])
		}
		// Blank the top line
		for c := 0; c < e.width; c++ {
			e.screen[e.scrollTop][c] = ' '
		}
	} else if e.cursorRow > 0 {
		e.cursorRow--
	}
}

// --- Test helper methods ---

// Scrollback returns all lines that have been scrolled into scrollback.
func (e *EmulatorTerminal) Scrollback() []string {
	return e.scrollback
}

// ScrollbackString returns the scrollback buffer as a single string.
func (e *EmulatorTerminal) ScrollbackString() string {
	return strings.Join(e.scrollback, "\n")
}

// NonBlankScrollback returns only non-empty lines from scrollback.
func (e *EmulatorTerminal) NonBlankScrollback() []string {
	var result []string
	for _, line := range e.scrollback {
		if line != "" {
			result = append(result, line)
		}
	}
	return result
}

// BlankScrollbackCount returns the number of blank lines in scrollback.
func (e *EmulatorTerminal) BlankScrollbackCount() int {
	count := 0
	for _, line := range e.scrollback {
		if line == "" {
			count++
		}
	}
	return count
}

// ScreenRow returns the content of a screen row as a trimmed string.
func (e *EmulatorTerminal) ScreenRow(row int) string {
	if row < 0 || row >= e.height {
		return ""
	}
	return strings.TrimRight(string(e.screen[row]), " ")
}

// ScreenString returns the entire visible screen as a string (rows joined by \n).
func (e *EmulatorTerminal) ScreenString() string {
	var lines []string
	for r := 0; r < e.height; r++ {
		lines = append(lines, strings.TrimRight(string(e.screen[r]), " "))
	}
	return strings.Join(lines, "\n")
}

// SetScreenRow sets the content of a screen row (for test setup).
func (e *EmulatorTerminal) SetScreenRow(row int, text string) {
	if row < 0 || row >= e.height {
		return
	}
	for c := 0; c < e.width; c++ {
		if c < len(text) {
			e.screen[row][c] = rune(text[c])
		} else {
			e.screen[row][c] = ' '
		}
	}
}

// DumpState returns a human-readable dump of the terminal state for debugging.
func (e *EmulatorTerminal) DumpState() string {
	var sb strings.Builder
	sb.WriteString(fmt.Sprintf("Terminal %dx%d, cursor=(%d,%d), scrollRegion=[%d,%d]\n",
		e.width, e.height, e.cursorRow, e.cursorCol, e.scrollTop, e.scrollBottom))
	sb.WriteString("--- Screen ---\n")
	for r := 0; r < e.height; r++ {
		sb.WriteString(fmt.Sprintf("  %2d: |%s|\n", r, string(e.screen[r])))
	}
	sb.WriteString(fmt.Sprintf("--- Scrollback (%d lines) ---\n", len(e.scrollback)))
	for i, line := range e.scrollback {
		if line == "" {
			sb.WriteString(fmt.Sprintf("  %2d: (blank)\n", i))
		} else {
			sb.WriteString(fmt.Sprintf("  %2d: |%s|\n", i, line))
		}
	}
	return sb.String()
}