# Plugin API

This document describes the API that plugins can use to interact with HexPatch.

## Functions

For the explanation of the types used in the functions, see the [Types](#types) section.

### Initialization

```lua
function init(context) end
```

This function is called when the plugin is loaded.

| Argument | Type | Description |
|----------|------|-------------|
|`context`|`Context`|The application context.|

### Events

#### On Open

```lua
function on_open(context) end
```

This function is called when a file is opened.

| Argument | Type | Description |
|----------|------|-------------|
|`context`|`Context`|The application context.|

#### On Close

```lua
function on_save(context) end
```

This function is called when a file is saved (both save and save as).

| Argument | Type | Description |
|----------|------|-------------|
|`context`|`Context`|The application context.|

#### On Edit

```lua
function on_edit(new_bytes, context) end
```

This function is called when the user edits the file, either directly or through a command.

| Argument | Type | Description |
|----------|------|-------------|
|`new_bytes`|`Data`|The new bytes of the file.|
|`context`|`Context`|The application context.|

#### On Key

```lua
function on_key(key_event, context) end
```

This function is called when a key is pressed.

| Argument | Type | Description |
|----------|------|-------------|
|`key_event`|`KeyEvent`|The key event.|
|`context`|`Context`|The application context.|

#### On Mouse

```lua
function on_mouse(mouse_event, context) end
```

This function is called when an action is performed with the mouse.

| Argument | Type | Description |
|----------|------|-------------|
|`mouse_event`|`MouseEvent`|The mouse event.|
|`context`|`Context`|The application context.|

#### On Focus

```lua
function on_focus(context) end
```

This function is called when the terminal gains focus.

| Argument | Type | Description |
|----------|------|-------------|
|`context`|`Context`|The application context.|

#### On Blur

```lua
function on_blur(context) end
```

This function is called when the terminal loses focus.

| Argument | Type | Description |
|----------|------|-------------|
|`context`|`Context`|The application context.|

#### On Paste

```lua
function on_paste(text, context) end
```

This function is called when text is pasted into the terminal.

| Argument | Type | Description |
|----------|------|-------------|
|`text`|`String`|The text that was pasted.|
|`context`|`Context`|The application context.|

#### On Resize

```lua
function on_resize(width, height, context) end
```

This function is called when the terminal is resized.
The size stored in the context is the old size, before the resize.

| Argument | Type | Description |
|----------|------|-------------|
|`width`|`usize`|The new width of the terminal.|
|`height`|`usize`|The new height of the terminal.|
|`context`|`Context`|The application context.|

### Commands

```lua
function COMMAND_NAME(context) end
```

This function is called when the user runs the command `COMMAND_NAME`.
The command must be registered using `context.add_command("COMMAND_NAME", "COMMAND_DESCRIPTION")`.

| Argument | Type | Description |
|----------|------|-------------|
|`context`|`Context`|The application context.|

### Popups

```lua
function FILL_POPUP_NAME(popup_context, context) end
```

This function is called each time the popup `FILL_POPUP_NAME` is drawn.
The popup must be opened using `context.open_popup("FILL_POPUP_NAME")`.

| Argument | Type | Description |
|----------|------|-------------|
|`popup_context`|`PopupContext`|The popup context.|
|`context`|`Context`|The application context.|

### Custom Headers

```lua
function HEADER_PARSER_NAME(header_context, context) end
```

This function is called whenever a new header is parsed, the first parser that returns a valid header will be used.
If during the parsing you decide that the header is not valid, you can raise an error or avoid setting values in the `header_context`.
The parser must be registered using `context.add_header_parser("HEADER_PARSER_NAME")`.

| Argument | Type | Description |
|----------|------|-------------|
|`header_context`|`HeaderContext`|The header context.|
|`context`|`Context`|The application context.|

## Types

### Context

This table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`screen_height`|`usize`|The height of the screen.|
|`screen_width`|`usize`|The width of the screen.|
|`data`|`Data`|The current file's data.|
|`offset`|`usize`|The current offset in the file.|
|`settings`|`Settings`|The settings of the application.|
|`current_instruction`|`Option<InstructionInfo>`|The current instruction at the current offset. `nil` if the current offset is not in an instruction or in a data section. The InstructionInfo type is explained at [InstructionInfo](#instructioninfo).|
|`header`|`Header`|The header of the file, if not valid or present, the default header will be used.|

And the following functions:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`log`|`(level: u8, message: String)`|Logs a message in the UI.|
|`add_command`|`(command_name: String)`|Registers a command, this must be called to make the command appear in the command list.|
|`remove_command`|`(command_name: String)`|Removes a command, this removes the command from the command list.|
|`add_header_parser`|`(parser_name: String)`|Registers a header parser, this must be called to make the parser be used when a new file is opened.|
|`remove_header_parser`|`(parser_name: String)`|Removes a header parser, this removes the parser from the list of parsers.|
|`open_popup`|`(popup_handler: String)`|Opens a popup, each time the popup is drawn the handler function is called|
|`get_popup`|`() -> Option<String>`|Returns the name of the `popup_handler` of the currently open popup if there is one opened by this plugin. `nil` otherwise.|
|`close_popup`|`(popup_handler: Option<String>)`|Closes a popup opened by this plugin. If `popup_handler` is not `nil` it will also check if that is the currently open popup. If no popup is open, this plugin does not own the currently open popup, or the provided handler does not match the function will raise an error.|
|`get_instant_now`|`() -> Instant`|Gets an instant relative to the time this function was called. The Instant type is explained at [Instant](#instant).|
|`jump_to`|`(file_address: usize)`|Makes the UI jump to the specified file address.|
|`get_fullscreen`|`() -> bool`|Gets whether the UI is in fullscreen mode.|
|`set_fullscreen`|`(fullscreen: bool)`|Sets whether the UI is in fullscreen mode.|
|`get_selected_pane`|`() -> String`|Gets the selected pane. The possible values are `"hex"` if the HexView is selected and `"view"` if TextView or AssemblyView are selected.|
|`set_selected_pane`|`(pane: String)`|Sets the selected pane. The possible values are `"hex"` to select the HexView and `"view"` to select TextView or AssemblyView.|
|`get_comments`|`() -> Table`|Gets the comments as a table, the keys are the file addresses and the values are the comments.|
|`get_comment`|`(file_address: usize) -> Option<String>`|Gets the comment at the specified file address. `nil` if there is no comment.|
|`set_comment`|`(file_address: usize, comment: Option<String>)`|Sets the comment at the specified file address. If `comment` is `nil` or an empty string, the comment will be removed.|

For more information on the types, see the following sections.

### Settings

This type contains the settings of the application.
A setting can be accessed using the `.` operator with its full name (dots are replaced with underscores).
e.g. `context.settings.color_address_selected`, `context.settings.key_up`, `context.settings.app_history_limit`.

WARNING: You should get and set the setting altogether, e.g. `context.settings.color_address_selected = {fg = "Red"}`. Trying to set a single field will not work.

To access custom settings, use the following functions:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`get_custom`|`(setting_name: String) -> CustomSetting`|Gets the value of a custom setting.|
|`set_custom`|`(setting_name: String, value: CustomSetting)`|Sets the value of a custom setting.|

### Data

A mutable vector of bytes.

The following functions are available:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`get`|`(index: usize) -> u8`|Gets the byte at the specified index. THE INDEX IS 0 BASED!|
|`set`|`(index: usize, value: u8)`|Sets the byte at the specified index. THE INDEX IS 0 BASED!|
|`len`|`() -> usize`|Gets the length of the vector.|

### KeyEvent

This table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`code`|`String`|The key that was pressed, a list of possible values is available at [KeyEvent.code](#keyeventcode)|
|`modifiers`|`Table`|A table containing the modifiers that were pressed, the entries are explained at [KeyEvent.modifiers](#keyeventmodifiers)|
|`kind`|`String`|The kind of key event, either `Press`, `Repeat` or `Release`|
|`state`|`Table`|A table containing the state of the keys, the entries are explained at [KeyEvent.state](#keyeventstate)|

#### KeyEvent.code

The following values are possible for the `code` field:

- `Backspace`
- `Enter`
- `Left`
- `Right`
- `Up`
- `Down`
- `Home`
- `End`
- `PageUp`
- `PageDown`
- `Tab`
- `BackTab`
- `Delete`
- `Insert`
- `Fn` where `n` is the function key number.
- `c` where `c` is the character that was pressed (can be either lower or upper case).
- `Null`
- `Esc`
- `CapsLock`
- `ScrollLock`
- `NumLock`
- `PrintScreen`
- `Pause`
- `Menu`
- `KeypadBegin`
- `Media(Play)`
- `Media(Pause)`
- `Media(PlayPause)`
- `Media(Reverse)`
- `Media(Stop)`
- `Media(FastForward)`
- `Media(Rewind)`
- `Media(TrackNext)`
- `Media(TrackPrevious)`
- `Media(Record)`
- `Media(LowerVolume)`
- `Media(RaiseVolume)`
- `Media(MuteVolume)`
- `Modifier(LeftShift)`
- `Modifier(LeftControl)`
- `Modifier(LeftAlt)`
- `Modifier(LeftSuper)`
- `Modifier(LeftHyper)`
- `Modifier(LeftMeta)`
- `Modifier(RightShift)`
- `Modifier(RightControl)`
- `Modifier(RightAlt)`
- `Modifier(RightSuper)`
- `Modifier(RightHyper)`
- `Modifier(RightMeta)`
- `Modifier(IsoLevel3Shift)`
- `Modifier(IsoLevel5Shift)`

#### KeyEvent.modifiers

The table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`alt`|`bool`|Whether the alt key was pressed.|
|`control`|`bool`|Whether the control key was pressed.|
|`hyper`|`bool`|Whether the hyper key was pressed.|
|`meta`|`bool`|Whether the meta key was pressed.|
|`shift`|`bool`|Whether the shift key was pressed.|
|`super`|`bool`|Whether the super key was pressed.|

#### KeyEvent.state

The table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`caps_lock`|`bool`|Whether the caps lock key is active.|
|`keypad`|`bool`|Whether the event origins from the keypad.|
|`num_lock`|`bool`|Whether the num lock key is active.|

### MouseEvent

This table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`kind`|`String`|The kind of mouse event, a list of possible values is available at [MouseEvent.kind](#mouseeventkind)|
|`column`|`usize`|The column of the terminal where the event happened.|
|`row`|`usize`|The row of the terminal where the event happened.|
|`modifiers`|`Table`|A table containing the modifiers that were pressed, the entries are explained at [KeyEvent.modifiers](#keyeventmodifiers) (This is the same table of the KeyEvent).|
|`location`|`Option<Table>`|A table containing the location of the mouse event, the entries are explained at [MouseEvent.location](#mouseeventlocation). This can be `nil` if the event is not on a specific component of the UI.|

#### MouseEvent.kind

The following values are possible for the `kind` field:

- `Down(Left)`
- `Down(Right)`
- `Down(Middle)`
- `Up(Left)`
- `Up(Right)`
- `Up(Middle)`
- `Drag(Left)`
- `Drag(Right)`
- `Drag(Middle)`
- `Moved`
- `ScrollDown`
- `ScrollUp`
- `ScrollLeft`
- `ScrollRight`

#### MouseEvent.location

This table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`info`|`Table`|A table containing info about the location of the mouse event, the entries are explained at [MouseEvent.location.info](#mouseeventlocationinfo).|
|`relative_location`|`Table`|A table containing the position of the event relative to the UI section (e.g. the offset from the top left corner of a popup when the popup window is clicked). The contents of this table are just `x` and `y` integer offsets from the top left corner of the container.|

##### MouseEvent.location.info

This table has different values depending on which component of the UI is involved with the event.
The table always contains the `type` key and depending on the corresponding value, it may contain other keys. These are the possible values for the `type` key and the corresponding additional keys:

- `"AddressView"`
  | Field | Type | Description |
  |-------|------|-------------|
  |`file_address`|`Option<u64>`|The file address pointed by the mouse during the event. `nil` if the event is not on an address.|
- `"HexView"`
  | Field | Type | Description |
  |-------|------|-------------|
  |`file_address`|`Option<u64>`|The file address of the byte pointed by the mouse during the event. `nil` if the event is not on a byte.|
  |`high`|`Option<bool>`|Whether the mouse is on the high or low half of the byte. `nil` if the event is not on a byte.|
  |`virtual_address`|`Option<u64>`|The virtual address of the byte pointed by the mouse during the event. `nil` if the event is not on a byte.|
  |`byte`|`Option<u8>`|The byte pointed by the mouse during the event. `nil` if the event is not on a byte.|
- `"TextView"`
  | Field | Type | Description |
  |-------|------|-------------|
  |`file_address`|`Option<u64>`|The file address of the character pointed by the mouse during the event. `nil` if the event is not on a character.|
  |`virtual_address`|`Option<u64>`|The virtual address of the character pointed by the mouse during the event. `nil` if the event is not on a character.|
  |`byte`|`Option<u8>`|The byte pointed by the mouse during the event. `nil` if the event is not on a character.|
  |`character`|`Option<char>`|The character pointed by the mouse during the event. `nil` if the event is not on a character or the byte is not a valid ASCII character.|
- `"AssemblyView"`
  | Field | Type | Description |
  |-------|------|-------------|
  |`section`|`Option<String>`|The section of the instruction pointed by the mouse during the event or the section pointed by the mouse during the event. `nil` if the event is not on an instruction nor on a section.|
  |`file_address`|`Option<u64>`|The file address of the instruction or section pointed by the mouse during the event. `nil` if the event is not on an instruction nor on a section.|
  |`virtual_address`|`Option<u64>`|The virtual address of the instruction or section pointed by the mouse during the event. `nil` if the event is not on an instruction nor on a section.|
  |`instruction`|`Option<String>`|The instruction pointed by the mouse during the event. `nil` if the event is not on an instruction.|
- `"StatusBar"`
- `"ScrollBar"`
- `"Popup"`
  | Field | Type | Description |
  |-------|------|-------------|
  |`name`|`String`|The name of the popup, possible names are listed below.|
  
  The possible names for popups are:

  - `"Open"`
  - `"Run"`
  - `"FindText"`
  - `"FindSymbol"`
  - `"Log"`
  - `"InsertText"`
  - `"Patch"`
  - `"JumpToAddress"`
  - `"QuitDirtySave"`
  - `"SaveAndQuit"`
  - `"SaveAs"`
  - `"Save"`
  - `"Help"`
  - `"Custom"`

### PopupContext

This table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`text`|`Text`|The content of the popup.|
|`title`|`MutString`|The title of the popup.|
|`height`|`MutUsize`|The height of the popup.|
|`width`|`MutUsize`|The width of the popup.|

### Text

To add text to a popup, use the following functions:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`push_line`|`(line: String)`|Adds a line of text to the popup.|
|`push_span`|`(span: String)`|Adds text without a newline to the popup.|
|`set_style`|`(style: Style)`|Sets the style of the text, this will be applied to every line or span until another style is set or `reset_style` is used.|
|`reset_style`|`()`|Resets the style to the default one. If this function is not called before the end of the FILL_POPUP function, the previously set style will replace the default style for the popup.|
|`set_alignment`|`(alignment: String)`|Sets the alignment of the text, the possible values are `left`, `center` and `right`, this will be applied to every line until another alignment is set or `reset_alignment` is used.|
|`reset_alignment`|`()`|Resets the alignment to the default one. If this function is not called before the end of the FILL_POPUP function, the previously set alignment will replace the default alignment for the popup.|

### MutString

This type is a mutable string, it can be manipulated using the following functions:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`get`|`() -> String`|Gets the string.|
|`set`|`(value: String)`|Sets the string.|

### MutUsize

This type is a mutable usize, it can be manipulated using the following functions:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`get`|`() -> usize`|Gets the value.|
|`set`|`(value: usize)`|Sets the value.|

### InstructionInfo

This table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`instruction`|`String`|The line of assembly code, the format depends on the architecture.|
|`physical_address`|`u64`|The offset in the file where the instruction starts.|
|`virtual_address`|`u64`|The virtual address at which the instruction will be mapped.|
|`size`|`usize`|The size of the instruction in bytes.|

### Header

This type has the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`bitness`|`u32`|The bitness of the file. (The default value is 64)|
|`entry_point`|`u64`|The virtual address of the entry point. (The default value is 0)|
|`architecture`|`String`|The architecture of the file, the possible values are listed in [Header.architecture](#headerarchitecture).|
|`sections`|`Vec<Section>`|The sections of the file, the vector is a lua vector. The Section type is explained at [Section](#section). (The default value is an empty vector.)|
|`text_section`|`Option<Section>`|The text section of the file. `nil` if not present. The Section type is explained at [Section](#section). (The default value is `nil`)|
|`symbols`|`Vec<String>`|The symbols of the file. (The default value is an empty vector.)|

And the following functions:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`symbol_to_address`|`(symbol: String) -> Option<u64>`|Gets the virtual address of a symbol. `nil` if no such symbol is found.|
|`virtual_to_physical_address`|`(virtual_address: u64) -> Option<u64>`|Gets the file offset of a virtual address. `nil` if no section contains the virtual address specified.|

#### Header.architecture

The following values are possible for the `architecture` field:

- `Unknown` (default value)
- `Aarch64`
- `Aarch64_Ilp32`
- `Arm`
- `Avr`
- `Bpf`
- `Csky`
- `I386`
- `X86_64`
- `X86_64_X32`
- `Hexagon`
- `LoongArch64`
- `Mips`
- `Mips64`
- `Msp430`
- `PowerPc`
- `PowerPc64`
- `Riscv32`
- `Riscv64`
- `S390x`
- `Sbf`
- `Sharc`
- `Sparc64`
- `Wasm32`
- `Wasm64`
- `Xtensa`

### Section

This type has the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`name`|`String`|The name of the section.|
|`virtual_address`|`u64`|The starting virtual address of the section.|
|`file_offset`|`u64`|The starting file offset of the section.|
|`size`|`usize`|The size of the section.|

### HeaderContext

This table contains the following fields:
| Function | Arguments | Description | Required |
|----------|-----------|-------------|----------|
|`set_bitness`|`(bitness: u8)`|Sets the bitness of the file. `bitness` must be either `32` or `64`| Yes |
|`set_entry`|`(entry_point: u64)`|Sets the virtual address of the entry point.| Yes |
|`set_endianness`|`(endianness: String)`|Sets the endianness of the file. `endianness` mut be either `little` or `big`.| Yes |
|`set_architecture`|`(architecture: String)`|Sets the architecture of the file. The possible values are listed in [Header.architecture](#headerarchitecture).| Yes |
|`add_section`|`(name: String, virtual_address: u64, file_offset: u64, size: u64)`|Adds a section to the file.| No |
|`add_symbol`|`(address: u64, name: String)`|Adds a symbol to the file.| No |

A function marked as required must be called to create a valid header. Those functions can only be called once.

### Style

This table contains the following fields:
| Field | Type | Description |
|-------|------|-------------|
|`fg`|`Option<Color>`|The foreground color. `nil` if transparent. The Color type is explained at [Color](#color).|
|`bg`|`Option<Color>`|The background color. `nil` if transparent. The Color type is explained at [Color](#color).|
|`underline`|`Option<Color>`|The underline color. `nil` if transparent. The Color type is explained at [Color](#color).|
|`add_modifier`|`u16`|A bitflag of the modifiers to add. The possible values are listed in [Style.modifier](#stylemodifier).|
|`sub_modifier`|`u16`|A bitflag of the modifiers to remove. The possible values are listed in [Style.modifier](#stylemodifier).|

### Style.modifier

The bitflags work as follows:
| Attribute | Bitflag |
|-----------|---------|
|`BOLD`|0b0000_0000_0001|
|`DIM`|0b0000_0000_0010|
|`ITALIC`|0b0000_0000_0100|
|`UNDERLINED`|0b0000_0000_1000|
|`SLOW_BLINK`|0b0000_0001_0000|
|`RAPID_BLINK`|0b0000_0010_0000|
|`REVERSED`|0b0000_0100_0000|
|`HIDDEN`|0b0000_1000_0000|
|`CROSSED_OUT`|0b0001_0000_0000|

### Color

This type is serialized and deserialized as a string.
The following values are possible:

- Standard colors:
  - `Black`
  - `Red`
  - `Green`
  - `Yellow`
  - `Blue`
  - `Magenta`
  - `Cyan`
  - `Gray` this is sometimes called `silver` or `white`, in this case `White` means bright white.
  - `DarkGray` this is sometimes called `light black` or `bright black`, in this case we use `DarkGray`
  - `LightRed`
  - `LightGreen`
  - `LightYellow`
  - `LightBlue`
  - `LightMagenta`
  - `LightCyan`
  - `White`
- Indexed 8-bit colors:
  - `#I` where I is an index from 0 to 255.
- RBG colors:
  - `#RRGGBB` where RR, GG and BB are hexadecimal values from 00 to FF.

### CustomSetting

A custom setting can be one of the following types:

- `bool`
- `i64`
- `f64`
- `String`
- `Style`
- `KeyEvent`

In the case of a `Style` or `KeyEvent`, the value is effectively a table with the same fields as the type.

### Instant

This type represents a point in time.

This type has the following functions:
| Function | Arguments | Description |
|----------|-----------|-------------|
|`elapsed`|`() -> f64`|Gets the time elapsed in seconds since the instant was created. This is a float so the precision should go up to nanoseconds.|
