lazy.nvim/lua/lazy/core/loader.lua

local Util = require("lazy.core.util")
local Config = require("lazy.core.config")
local Handler = require("lazy.core.handler")

local M = {}

---@type LazyPlugin[]
M.loading = {}
M.init_done = false
---@type table<string,true>
M.disabled_rtp_plugins = { packer_compiled = true }

function M.setup()
  -- install missing plugins
  if Config.options.install.missing then
    Util.track("install")
    for _, plugin in pairs(Config.plugins) do
      if not plugin._.installed then
        for _, colorscheme in ipairs(Config.options.install.colorscheme) do
          if pcall(vim.cmd.colorscheme, colorscheme) then
            break
          end
        end
        require("lazy.manage").install({ wait = true })
        break
      end
    end
    Util.track()
  end

  -- setup handlers
  Util.track("handlers")
  Handler.setup()
  Util.track()

  for _, file in ipairs(Config.options.performance.rtp.disabled_plugins) do
    M.disabled_rtp_plugins[file] = true
  end

  vim.api.nvim_create_autocmd("ColorSchemePre", {
    callback = function(event)
      M.colorscheme(event.match)
    end,
  })

  -- autoload opt plugins
  table.insert(package.loaders, M.autoload)
end

-- Startup sequence
-- 1. load any start plugins and do init
function M.startup()
  Util.track({ start = "startup" })

  -- load filetype.lua first since plugins might depend on that
  M.source(vim.env.VIMRUNTIME .. "/filetype.lua")

  -- backup original rtp
  local rtp = vim.opt.rtp:get()

  -- 1. run plugin init
  Util.track({ start = "init" })
  for _, plugin in pairs(Config.plugins) do
    if plugin.init then
      Util.track({ plugin = plugin.name, init = "init" })
      Util.try(plugin.init, "Failed to run `init` for **" .. plugin.name .. "**")
      Util.track()
    end
  end
  Util.track()

  -- 2. load start plugin
  Util.track({ start = "start" })
  for _, plugin in pairs(Config.plugins) do
    if plugin.lazy == false and not plugin._.loaded then
      M.load(plugin, { start = "start" })
    end
  end
  Util.track()

  -- 3. load plugins from rtp, excluding after
  Util.track({ start = "rtp plugins" })
  for _, path in ipairs(rtp) do
    if not path:find("after/?$") then
      M.packadd(path)
    end
  end
  Util.track()

  -- 4. load after plugins
  Util.track({ start = "after" })
  for _, path in ipairs(vim.opt.rtp:get()) do
    if path:find("after/?$") then
      M.source_runtime(path, "plugin")
    end
  end
  Util.track()

  M.init_done = true

  Util.track()
end

---@class Loader
---@param plugins string|LazyPlugin|string[]|LazyPlugin[]
---@param reason {[string]:string}
function M.load(plugins, reason)
  ---@diagnostic disable-next-line: cast-local-type
  plugins = (type(plugins) == "string" or plugins.name) and { plugins } or plugins
  ---@cast plugins (string|LazyPlugin)[]

  for _, plugin in pairs(plugins) do
    plugin = type(plugin) == "string" and Config.plugins[plugin] or plugin
    ---@cast plugin LazyPlugin

    if not plugin._.loaded then
      ---@diagnostic disable-next-line: assign-type-mismatch
      plugin._.loaded = {}
      for k, v in pairs(reason) do
        plugin._.loaded[k] = v
      end
      if #M.loading > 0 then
        plugin._.loaded.plugin = M.loading[#M.loading].name
      elseif reason.require then
        plugin._.loaded.source = Util.get_source()
      end

      table.insert(M.loading, plugin)

      Util.track({ plugin = plugin.name, start = reason.start })
      Handler.disable(plugin)

      vim.opt.runtimepath:prepend(plugin.dir)
      local after = plugin.dir .. "/after"
      if vim.loop.fs_stat(after) then
        vim.opt.runtimepath:append(after)
      end

      if plugin.dependencies then
        M.load(plugin.dependencies, {})
      end

      M.packadd(plugin.dir)
      if plugin.config then
        Util.try(plugin.config, "Failed to run `config` for " .. plugin.name)
      end

      plugin._.loaded.time = Util.track().time
      table.remove(M.loading)
      vim.schedule(function()
        vim.cmd("do User LazyRender")
      end)
    end
  end
end

---@param path string
function M.packadd(path)
  M.source_runtime(path, "plugin")
  M.ftdetect(path)
  if M.init_done then
    M.source_runtime(path, "after/plugin")
  end
end

---@param path string
function M.ftdetect(path)
  vim.cmd("augroup filetypedetect")
  M.source_runtime(path, "ftdetect")
  vim.cmd("augroup END")
end

---@param ... string
function M.source_runtime(...)
  local dir = table.concat({ ... }, "/")
  ---@type string[]
  local files = {}
  Util.walk(dir, function(path, name, t)
    local ext = name:sub(-3)
    name = name:sub(1, -5)
    if (t == "file" or t == "link") and (ext == "lua" or ext == "vim") and not M.disabled_rtp_plugins[name] then
      files[#files + 1] = path
    end
  end)
  -- plugin files are sourced alphabetically per directory
  table.sort(files)
  for _, path in ipairs(files) do
    M.source(path)
  end
end

function M.source(path)
  Util.track({ runtime = path })
  Util.try(function()
    vim.cmd("silent source " .. path)
  end, "Failed to source `" .. path .. "`")
  Util.track()
end

function M.colorscheme(name)
  if vim.tbl_contains(vim.fn.getcompletion("", "color"), name) then
    return
  end
  for _, plugin in pairs(Config.plugins) do
    if not plugin._.loaded then
      for _, ext in ipairs({ "lua", "vim" }) do
        local path = plugin.dir .. "/colors/" .. name .. "." .. ext
        if vim.loop.fs_stat(path) then
          return M.load(plugin, { colorscheme = name })
        end
      end
    end
  end
end

-- This loader is added as the very last one.
-- This only hits when the modname is not cached and
-- even then only once per plugin. So pretty much never.
---@param modname string
function M.autoload(modname)
  -- check if a lazy plugin should be loaded
  for _, plugin in pairs(Config.plugins) do
    if not (plugin._.loaded or plugin.module == false) then
      for _, pattern in ipairs({ ".lua", "/init.lua" }) do
        local path = plugin.dir .. "/lua/" .. modname:gsub("%.", "/") .. pattern
        if vim.loop.fs_stat(path) then
          M.load(plugin, { require = modname })
          -- check if the module has been loaded in the meantime
          if type(package.loaded[modname]) == "table" then
            local mod = package.loaded[modname]
            return function()
              return mod
            end
          end
          local chunk, err = loadfile(path)
          return chunk or error(err)
        end
      end
    end
  end
  return modname .. " not found in lazy plugins"
end

return M