scritcher/src/plugin.zig

const std = @import("std");

const c = @import("lv2_helpers.zig").c;

const ImageError = @import("image.zig").ImageError;

/// Control port
pub const Param = struct {
    /// Port symbol
    sym: []const u8,

    /// Control value
    value: f32,
};

/// List of parameters to be set to control ports.
pub const ParamList = std.ArrayList(Param);

/// Represents a relative position in the image
pub const Position = struct {
    split: usize,
    index: usize,
};

/// Represents the starting context for a single plugin run.
pub const Context = struct {
    allocator: *std.mem.Allocator,
    world: *c.LilvWorld,
    plugin: ?*const c.LilvPlugin,

    // they should both be 1.
    n_audio_in: usize = 0,
    n_audio_out: usize = 0,
};

pub fn makeContext(allocator: *std.mem.Allocator, plugin_uri: []const u8) !Context {
    const cstr_plugin_uri = try std.cstr.addNullByte(allocator, plugin_uri);
    var world = c.lilv_world_new().?;

    c.lilv_world_load_all(world);
    var uri: *c.LilvNode = c.lilv_new_uri(world, cstr_plugin_uri.ptr) orelse blk: {
        std.debug.warn("Invalid plugin URI <{}>\n", plugin_uri);
        return ImageError.InvalidPlugin;
    };

    const plugins: *const c.LilvPlugins = c.lilv_world_get_all_plugins(world);

    var plugin: *const c.LilvPlugin = c.lilv_plugins_get_by_uri(plugins, uri) orelse blk: {
        std.debug.warn("Plugin <{}> not found\n", plugin_uri);
        return ImageError.UnknownPlugin;
    };

    c.lilv_node_free(uri);

    return Context{ .allocator = allocator, .world = world, .plugin = plugin };
}