discordo-plus/images.plan

# Image Viewing & Save Feature — Implementation Plan

## Overview

Add lightweight image viewing and saving for image attachments (jpg, jpeg, png, webp, gif)
in discordo. Uses an external viewer (`imv` by default, configurable) that can be dismissed
with `q`. Adds a new keybind to save the highlighted message's image attachment to a
user-configured directory.

---

## Bug Fix (prerequisite)

### 1. Fix broken attachment link rendering

**File:** `internal/ui/chat/messages_list.go` ~line 500

**Problem:** Attachment URLs are rendered with a literal `\n` inside a single
`builder.Write()` call:

```go
builder.Write(a.Filename+":\n"+a.URL, attachmentStyle)
```

The `\n` is embedded in the segment text but `tview.LineBuilder` does not split
on `\n` within a `Write()` call — the newline character ends up treated as inline
content, corrupting the URL display and breaking the link.

**Fix:** Split into two writes separated by `builder.NewLine()`:

```go
builder.Write(a.Filename+":", attachmentStyle)
builder.NewLine()
builder.Write(a.URL, attachmentStyle.Url(a.URL))
```

This also applies the `.Url()` style metadata so the link is properly clickable
in terminals that support OSC 8 hyperlinks.

---

## Feature Changes

### 2. Add config fields for image viewer and save directory

**File:** `internal/config/config.go`

Add two new fields to the `Config` struct:

```go
ImageViewer  string `toml:"image_viewer"`   // e.g. "imv", "feh", "sxiv"
ImageSaveDir string `toml:"image_save_dir"` // e.g. "~/Pictures/discordo"
```

**File:** `internal/config/config.toml`

Add defaults:

```toml
# Program used to view image attachments. Must accept a file path as its
# first argument. Set to "default" to use xdg-open / open.
image_viewer = "imv"

# Directory where images are saved with the save_image keybind.
# Supports ~ for home directory. Leave empty to use the current directory.
image_save_dir = ""
```

**File:** `internal/config/config.go` — `applyDefaults()`

- Expand `~` in `ImageSaveDir` to the user's home directory.
- If `ImageViewer` is `"default"` or empty, fall back to `open.Start()` behavior
  (system default).

### 3. Add `save_image` keybind

**File:** `internal/config/keybinds.go`

Add to `MessagesListKeybinds`:

```go
SaveImage Keybind `toml:"save_image"`
```

Default key: `S` (capital S — currently unused in messages list).

**File:** `internal/config/config.toml`

```toml
# Save the selected message's image attachment to image_save_dir.
save_image = "S"
```

### 4. Change `openAttachment()` to use configured image viewer

**File:** `internal/ui/chat/messages_list.go`

Modify `openAttachment()` (line 1183):

- After downloading the attachment to cache (existing logic), instead of calling
  `open.Start(path)`, check `ml.cfg.ImageViewer`:
  - If set and not `"default"`: exec the viewer with the cached file path as arg,
    e.g. `exec.Command(ml.cfg.ImageViewer, path).Run()`.
  - If `"default"` or empty: fall back to `open.Start(path)` (current behavior).
- The viewer command runs in a goroutine. While the viewer is open, discordo's
  TUI is suspended (same pattern as the external editor: `ml.chatView.app.Suspend()`
  + resume after the command exits). This lets terminal-based viewers like `imv`
  take over the terminal cleanly.

Affected types: jpg, jpeg, png, webp, gif — filter on `attachment.ContentType`
matching `image/jpeg`, `image/png`, `image/webp`, `image/gif`. For non-image
attachments, keep existing `open.Start(url)` behavior.

### 5. Implement `saveImage()` function and wire up keybind

**File:** `internal/ui/chat/messages_list.go`

New function `saveImage()`:

```
func (ml *messagesList) saveImage()
```

Logic:
1. Get the selected message via `ml.selectedMessage()`.
2. Filter `msg.Attachments` to only image types (jpg, jpeg, png, webp, gif) by
   checking `attachment.ContentType`.
3. If no image attachments, return early (no-op).
4. If one image: download and save directly.
5. If multiple images: show the attachments picker (reuse existing
   `showAttachmentsList` pattern but with save actions instead of open actions).
6. Download the image via HTTP (reuse the download logic from `openAttachment`
   — extract into a shared helper `downloadAttachment()` that returns the local
   file path).
7. Copy the file from cache to `ml.cfg.ImageSaveDir/filename`. If
   `ImageSaveDir` is empty, save to the current working directory.
8. Log success/failure via `slog`.

**File:** `internal/ui/chat/messages_list.go` — keybind registration

In the function that registers messages list keybinds (look for where `Open` keybind
is registered), add the `SaveImage` keybind pointing to `ml.saveImage`.

### 6. Extract shared download helper

**File:** `internal/ui/chat/messages_list.go`

Refactor the HTTP download + cache write logic currently in `openAttachment()` into:

```go
func (ml *messagesList) downloadToCache(attachment discord.Attachment) (string, error)
```

Returns the local cached file path. Used by both `openAttachment()` and `saveImage()`.

---

## File Change Summary

| File | Changes |
|------|---------|
| `internal/ui/chat/messages_list.go` | Fix attachment link rendering; refactor download logic; modify `openAttachment()` to use configured viewer with app suspend/resume; add `saveImage()`; register new keybind |
| `internal/config/config.go` | Add `ImageViewer` and `ImageSaveDir` fields; expand `~` in defaults |
| `internal/config/config.toml` | Add `image_viewer`, `image_save_dir`, and `save_image` keybind defaults |
| `internal/config/keybinds.go` | Add `SaveImage` keybind to `MessagesListKeybinds` and default |

---

## Implementation Order

1. Fix the `\n` attachment link bug (quick, independent)
2. Add config fields + defaults (`config.go`, `config.toml`)
3. Add `SaveImage` keybind (`keybinds.go`, `config.toml`)
4. Extract `downloadToCache()` helper from `openAttachment()`
5. Modify `openAttachment()` to use configured viewer + suspend/resume
6. Implement `saveImage()` and wire up keybind

---

## Notes

- `imv` is chosen as the default viewer because it's lightweight, supports
  Wayland and X11, handles all target formats (jpg, png, webp, gif) out of
  the box via FreeImage/libnsgif, and exits on `q` by default.
- Users who prefer X11-only can set `image_viewer = "feh"` (note: `feh` lacks
  WebP support on many distros).
- Users on macOS can set `image_viewer = "open"` or `image_viewer = "default"`.
- The suspend/resume pattern for the viewer follows the same approach already
  used for the external editor (see `message_input.go` `openEditor` flow).
- No new Go dependencies are needed — `os/exec` is in the stdlib and HTTP
  download logic already exists.