1 files changed, 203 insertions, 0 deletions
diff --git a/lua/mason-core/ui/init.lua b/lua/mason-core/ui/init.lua
new file mode 100644
index 00000000..0b288b20
--- /dev/null
+++ b/lua/mason-core/ui/init.lua
@@ -0,0 +1,203 @@
+local _ = require "mason-core.functional"
+local M = {}
+
+---@alias NodeType
+---| '"NODE"'
+---| '"CASCADING_STYLE"'
+---| '"VIRTUAL_TEXT"'
+---| '"DIAGNOSTICS"'
+---| '"HL_TEXT"'
+---| '"KEYBIND_HANDLER"'
+---| '"STICKY_CURSOR"'
+
+---@alias INode Node | HlTextNode | CascadingStyleNode | VirtualTextNode | KeybindHandlerNode | DiagnosticsNode | StickyCursorNode
+
+---@param children INode[]
+function M.Node(children)
+    ---@class Node
+    local node = {
+        type = "NODE",
+        children = children,
+    }
+    return node
+end
+
+---@param lines_with_span_tuples string[][]|string[]
+function M.HlTextNode(lines_with_span_tuples)
+    if type(lines_with_span_tuples[1]) == "string" then
+        -- this enables a convenience API for just rendering a single line (with just a single span)
+        lines_with_span_tuples = { { lines_with_span_tuples } }
+    end
+    ---@class HlTextNode
+    local node = {
+        type = "HL_TEXT",
+        lines = lines_with_span_tuples,
+    }
+    return node
+end
+
+local create_unhighlighted_lines = _.map(function(line)
+    return { { line, "" } }
+end)
+
+---@param lines string[]
+function M.Text(lines)
+    return M.HlTextNode(create_unhighlighted_lines(lines))
+end
+
+---@alias CascadingStyle
+---| '"INDENT"'
+---| '"CENTERED"'
+
+---@param styles CascadingStyle[]
+---@param children INode[]
+function M.CascadingStyleNode(styles, children)
+    ---@class CascadingStyleNode
+    local node = {
+        type = "CASCADING_STYLE",
+        styles = styles,
+        children = children,
+    }
+    return node
+end
+
+---@param virt_text string[][] @List of (text, highlight) tuples.
+function M.VirtualTextNode(virt_text)
+    ---@class VirtualTextNode
+    local node = {
+        type = "VIRTUAL_TEXT",
+        virt_text = virt_text,
+    }
+    return node
+end
+
+---@param diagnostic {message: string, severity: integer, source: string|nil}
+function M.DiagnosticsNode(diagnostic)
+    ---@class DiagnosticsNode
+    local node = {
+        type = "DIAGNOSTICS",
+        diagnostic = diagnostic,
+    }
+    return node
+end
+
+---@param condition boolean
+---@param node INode | fun(): INode
+---@param default_val any
+function M.When(condition, node, default_val)
+    if condition then
+        if type(node) == "function" then
+            return node()
+        else
+            return node
+        end
+    end
+    return default_val or M.Node {}
+end
+
+---@param key string @The keymap to register to. Example: "<CR>".
+---@param effect string @The effect to call when keymap is triggered by the user.
+---@param payload any @The payload to pass to the effect handler when triggered.
+---@param is_global boolean|nil @Whether to register the keybind to apply on all lines in the buffer.
+function M.Keybind(key, effect, payload, is_global)
+    ---@class KeybindHandlerNode
+    local node = {
+        type = "KEYBIND_HANDLER",
+        key = key,
+        effect = effect,
+        payload = payload,
+        is_global = is_global or false,
+    }
+    return node
+end
+
+function M.EmptyLine()
+    return M.Text { "" }
+end
+
+---@param rows string[][][] @A list of rows to include in the table. Each row consists of an array of (text, highlight) tuples (aka spans).
+function M.Table(rows)
+    local col_maxwidth = {}
+    for i = 1, #rows do
+        local row = rows[i]
+        for j = 1, #row do
+            local col = row[j]
+            local content = col[1]
+            col_maxwidth[j] = math.max(vim.api.nvim_strwidth(content), col_maxwidth[j] or 0)
+        end
+    end
+
+    for i = 1, #rows do
+        local row = rows[i]
+        for j = 1, #row do
+            local col = row[j]
+            local content = col[1]
+            col[1] = content .. string.rep(" ", col_maxwidth[j] - vim.api.nvim_strwidth(content) + 1) -- +1 for default minimum padding
+        end
+    end
+
+    return M.HlTextNode(rows)
+end
+
+---@param opts { id: string }
+function M.StickyCursor(opts)
+    ---@class StickyCursorNode
+    local node = {
+        type = "STICKY_CURSOR",
+        id = opts.id,
+    }
+    return node
+end
+
+---Makes it possible to create stateful animations by progressing from the start of a range to the end.
+---This is done in "ticks", in accordance with the provided options.
+---@param opts {range: integer[], delay_ms: integer, start_delay_ms: integer, iteration_delay_ms: integer}
+function M.animation(opts)
+    local animation_fn = opts[1]
+    local start_tick, end_tick = opts.range[1], opts.range[2]
+    local is_animating = false
+
+    local function start_animation()
+        if is_animating then
+            return
+        end
+        local tick, start
+
+        tick = function(current_tick)
+            animation_fn(current_tick)
+            if current_tick < end_tick then
+                vim.defer_fn(function()
+                    tick(current_tick + 1)
+                end, opts.delay_ms)
+            else
+                is_animating = false
+                if opts.iteration_delay_ms then
+                    start(opts.iteration_delay_ms)
+                end
+            end
+        end
+
+        start = function(delay_ms)
+            is_animating = true
+            if delay_ms then
+                vim.defer_fn(function()
+                    tick(start_tick)
+                end, delay_ms)
+            else
+                tick(start_tick)
+            end
+        end
+
+        start(opts.start_delay_ms)
+
+        local function cancel()
+            is_animating = false
+        end
+
+        return cancel
+    end
+
+    return start_animation
+end
+
+return M