local Cache = require("lazy.core.cache")
local Config = require("lazy.core.config")
local Handler = require("lazy.core.handler")
local Plugin = require("lazy.core.plugin")
local Util = require("lazy.core.util")

---@class LazyCoreLoader
local M = {}

local DEFAULT_PRIORITY = 50

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

function M.disable_rtp_plugin(plugin)
  M.disabled_rtp_plugins[plugin] = true
end

function M.setup()
  for _, file in ipairs(Config.options.performance.rtp.disabled_plugins) do
    M.disable_rtp_plugin(file)
  end

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

  -- load the plugins
  Plugin.load()
  Handler.init()

  -- install missing plugins
  if Config.options.install.missing then
    Util.track("install")
    local count = 0
    while M.install_missing() do
      count = count + 1
      if count > 5 then
        Util.error("Too many rounds of missing plugins")
        break
      end
    end
    Util.track()
  end
  Config.mapleader = vim.g.mapleader
  Config.maplocalleader = vim.g.maplocalleader

  -- report any warnings & errors
  Config.spec:report()

  -- setup handlers
  Util.track("handlers")
  Handler.setup()
  M.did_handlers = true
  Util.track()
end

-- this will incrementally install missing plugins
-- multiple rounds can happen when importing a spec from a missing plugin
function M.install_missing()
  for _, plugin in pairs(Config.plugins) do
    local installed = plugin._.installed
    local has_errors = Plugin.has_errors(plugin)

    if not has_errors and not (installed and not plugin._.build) then
      for _, colorscheme in ipairs(Config.options.install.colorscheme) do
        if colorscheme == "default" then
          break
        end
        M.colorscheme(colorscheme)
        if vim.g.colors_name or pcall(vim.cmd.colorscheme, colorscheme) then
          break
        end
      end
      Cache.reset()
      require("lazy.manage").install({ wait = true, lockfile = true, clear = false })
      -- remove any installed plugins from indexed, so cache will index again
      for _, p in pairs(Config.plugins) do
        if p._.installed then
          Cache.reset(p.dir)
        end
      end
      -- reload plugins
      Plugin.load()
      return true
    end
  end
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() --[[@as string[] ]]

  -- 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(function()
        plugin.init(plugin)
      end, "Failed to run `init` for **" .. plugin.name .. "**")
      Util.track()
    end
  end
  Util.track()

  -- 2. load start plugin
  Util.track({ start = "start" })
  for _, plugin in ipairs(M.get_start_plugins()) do
    -- plugin may be loaded by another plugin in the meantime
    if not plugin._.loaded then
      M.load(plugin, { start = "start" })
    end
  end
  Util.track()

  -- 3. load plugins from the original rtp, excluding after
  Util.track({ start = "rtp plugins" })
  for _, path in ipairs(rtp) do
    if not path:find("after/?$") then
      -- these paths don't will already have their ftdetect ran,
      -- by sourcing filetype.lua above, so skip them
      M.did_ftdetect[path] = path
      M.packadd(path)
    end
  end
  Util.track()

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

  M.init_done = true

  Util.track()
end

function M.get_start_plugins()
  ---@type LazyPlugin[]
  local start = {}
  for _, plugin in pairs(Config.plugins) do
    if not plugin._.loaded and (plugin._.rtp_loaded or plugin.lazy == false) then
      start[#start + 1] = plugin
    end
  end
  table.sort(start, function(a, b)
    local ap = a.priority or DEFAULT_PRIORITY
    local bp = b.priority or DEFAULT_PRIORITY
    return ap > bp
  end)
  return start
end

---@class Loader
---@param plugins string|LazyPlugin|string[]|LazyPlugin[]
---@param reason {[string]:string}
---@param opts? {force:boolean} when force is true, we skip the cond check
function M.load(plugins, reason, opts)
  ---@diagnostic disable-next-line: cast-local-type
  plugins = (type(plugins) == "string" or plugins.name) and { plugins } or plugins
  ---@cast plugins (string|LazyPlugin)[]
  local queue = {}
  for _, plugin in pairs(plugins) do
    if type(plugin) == "string" then
      if Config.plugins[plugin] then
        plugin = Config.plugins[plugin]
      elseif Config.spec.disabled[plugin] then
        goto continue
      else
        Util.error("Plugin " .. plugin .. " not found")
        goto continue
      end
    end
    if not plugin._.loaded then
      table.insert(queue, plugin)
    end
    ::continue::
  end

  table.sort(queue,function (a,b)
    return a.priority and b.priority and a.priority>b.priority
  end)

  for _,plugin in ipairs(queue) do
    M._load(plugin, reason, opts)
  end
end

---@param plugin LazyPlugin
function M.deactivate(plugin)
  if not plugin._.loaded then
    return
  end

  local main = M.get_main(plugin)

  if main then
    Util.try(function()
      local mod = require(main)
      if mod.deactivate then
        mod.deactivate(plugin)
      end
    end, "Failed to deactivate plugin " .. plugin.name)
  end

  -- execute deactivate when needed
  if plugin.deactivate then
    Util.try(function()
      plugin.deactivate(plugin)
    end, "Failed to deactivate plugin " .. plugin.name)
  end

  -- disable handlers
  Handler.disable(plugin)

  -- clear plugin properties cache
  plugin._.cache = nil

  -- remove loaded lua modules
  Util.walkmods(plugin.dir .. "/lua", function(modname)
    package.loaded[modname] = nil
    package.preload[modname] = nil
  end)

  -- clear vim.g.loaded_ for plugins
  Util.ls(plugin.dir .. "/plugin", function(_, name, type)
    if type == "file" then
      vim.g["loaded_" .. name:gsub("%..*", "")] = nil
    end
  end)
  -- set as not loaded
  plugin._.loaded = nil
end

--- reload a plugin
---@param plugin LazyPlugin|string
function M.reload(plugin)
  if type(plugin) == "string" then
    plugin = Config.plugins[plugin]
  end

  if not plugin then
    error("Plugin not found")
  end

  local load = plugin._.loaded ~= nil
  M.deactivate(plugin)

  -- enable handlers
  Handler.enable(plugin)

  -- run init
  if plugin.init then
    Util.try(function()
      plugin.init(plugin)
    end, "Failed to run `init` for **" .. plugin.name .. "**")
  end

  -- if this is a start plugin, load it now
  if plugin.lazy == false then
    load = true
  end

  local events = plugin._.handlers and plugin._.handlers.event and plugin._.handlers.event or {}

  for _, event in pairs(events) do
    if event.id:find("VimEnter") or event.id:find("UIEnter") or event.id:find("VeryLazy") then
      load = true
      break
    end
  end

  -- reload any vimscript files for this plugin
  local scripts = vim.fn.getscriptinfo()
  local loaded_scripts = {}
  for _, s in ipairs(scripts) do
    ---@type string
    local path = s.name
    if
      path:sub(-4) == ".vim"
      and path:find(plugin.dir, 1, true) == 1
      and not path:find("/plugin/", 1, true)
      and not path:find("/ftplugin/", 1, true)
    then
      loaded_scripts[#loaded_scripts + 1] = path
    end
  end

  if load then
    M.load(plugin, { start = "reload" })
    for _, s in ipairs(loaded_scripts) do
      M.source(s)
    end
  end
end

---@param plugin LazyPlugin
---@param reason {[string]:string}
---@param opts? {force:boolean} when force is true, we skip the cond check
function M._load(plugin, reason, opts)
  if not plugin._.installed then
    return Util.error("Plugin " .. plugin.name .. " is not installed")
  end

  if plugin._.cond == false and not (opts and opts.force) then
    return
  end

  if not Handler.did_setup then
    Util.try(function()
      Handler.enable(plugin)
    end, "Failed to setup handlers for " .. plugin.name)
  end

  ---@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)

  M.add_to_rtp(plugin)

  if plugin._.pkg and plugin._.pkg.source == "rockspec" then
    M.add_to_luapath(plugin)
  end

  if plugin.dependencies then
    Util.try(function()
      M.load(plugin.dependencies, {})
    end, "Failed to load deps for " .. plugin.name)
  end

  M.packadd(plugin.dir)
  if plugin.config or plugin.opts then
    M.config(plugin)
  end

  plugin._.loaded.time = Util.track().time
  table.remove(M.loading)
  vim.schedule(function()
    vim.api.nvim_exec_autocmds("User", { pattern = "LazyLoad", modeline = false, data = plugin.name })
    vim.api.nvim_exec_autocmds("User", { pattern = "LazyRender", modeline = false })
  end)
end

--- runs plugin config
---@param plugin LazyPlugin
function M.config(plugin)
  local fn
  if type(plugin.config) == "function" then
    fn = function()
      local opts = Plugin.values(plugin, "opts", false)
      plugin.config(plugin, opts)
    end
  else
    local main = M.get_main(plugin)
    if main then
      fn = function()
        local opts = Plugin.values(plugin, "opts", false)
        require(main).setup(opts)
      end
    else
      return Util.error(
        "Lua module not found for config of " .. plugin.name .. ". Please use a `config()` function instead"
      )
    end
  end
  Util.try(fn, "Failed to run `config` for " .. plugin.name)
end

---@param plugin LazyPlugin
function M.get_main(plugin)
  if plugin.main then
    return plugin.main
  end
  if plugin.name ~= "mini.nvim" and plugin.name:match("^mini%..*$") then
    return plugin.name
  end
  local normname = Util.normname(plugin.name)
  ---@type string[]
  local mods = {}
  for _, mod in ipairs(Cache.find("*", { all = true, rtp = false, paths = { plugin.dir } })) do
    local modname = mod.modname
    mods[#mods + 1] = modname
    local modnorm = Util.normname(modname)
    -- if we found an exact match, then use that
    if modnorm == normname then
      mods = { modname }
      break
    end
  end

  return #mods == 1 and mods[1] or nil
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)
  if not M.did_ftdetect[path] then
    M.did_ftdetect[path] = path
    vim.cmd("augroup filetypedetect")
    M.source_runtime(path, "ftdetect")
    vim.cmd("augroup END")
  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

-- This does the same as runtime.c:add_pack_dir_to_rtp
-- * find first after
-- * find lazy pack path
-- * insert right after lazy pack path or right before first after or at the end
-- * insert after dir right before first after or append to the end
---@param plugin LazyPlugin
function M.add_to_rtp(plugin)
  local rtp = vim.api.nvim_get_runtime_file("", true)
  local idx_dir, idx_after

  for i, path in ipairs(rtp) do
    if Util.is_win then
      path = Util.norm(path)
    end
    if path == Config.me then
      idx_dir = i + 1
    elseif not idx_after and path:sub(-6, -1) == "/after" then
      idx_after = i + 1 -- +1 to offset the insert of the plugin dir
      idx_dir = idx_dir or i
      break
    end
  end

  table.insert(rtp, idx_dir or (#rtp + 1), plugin.dir)

  local after = plugin.dir .. "/after"
  if vim.uv.fs_stat(after) then
    table.insert(rtp, idx_after or (#rtp + 1), after)
  end

  ---@type vim.Option
  vim.opt.rtp = rtp
end

---@param plugin LazyPlugin
function M.add_to_luapath(plugin)
  local root = Config.options.rocks.root .. "/" .. plugin.name
  local path = root .. "/share/lua/5.1"
  local cpath = root .. "/lib/lua/5.1"
  local cpath2 = root .. "/lib64/lua/5.1"

  package.path = package.path .. ";" .. path .. "/?.lua;" .. path .. "/?/init.lua;"
  package.cpath = package.cpath .. ";" .. cpath .. "/?." .. (jit.os:find("Windows") and "dll" or "so") .. ";"
  package.cpath = package.cpath .. ";" .. cpath2 .. "/?." .. (jit.os:find("Windows") and "dll" or "so") .. ";"
end

function M.source(path)
  Util.track({ runtime = path })
  Util.try(function()
    vim.cmd("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.uv.fs_stat(path) then
          return M.load(plugin, { colorscheme = name })
        end
      end
    end
  end
end

function M.auto_load(modname, modpath)
  local plugin = Plugin.find(modpath, { fast = not M.did_handlers })
  if plugin then
    plugin._.rtp_loaded = true
    -- don't load if:
    -- * handlers haven't been setup yet
    -- * we're loading specs
    -- * the plugin is already loaded
    if M.did_handlers and not (Plugin.loading or plugin._.loaded) then
      if plugin.module == false then
        error("Plugin " .. plugin.name .. " is not loaded and is configured with module=false")
      end
      M.load(plugin, { require = modname })
      if plugin._.cond == false then
        error("You're trying to load `" .. plugin.name .. "` for which `cond==false`")
      end
    end
  end
end

---@param modname string
function M.loader(modname)
  local paths, cached = Util.get_unloaded_rtp(modname, { cache = true })
  local ret = Cache.find(modname, { rtp = false, paths = paths })[1]

  if not ret and cached then
    paths = Util.get_unloaded_rtp(modname)
    ret = Cache.find(modname, { rtp = false, paths = paths })[1]
  end

  if ret then
    -- explicitly set to nil to prevent loading errors
    package.loaded[modname] = nil
    M.auto_load(modname, ret.modpath)
    local mod = package.loaded[modname]
    if type(mod) == "table" then
      return function()
        return mod
      end
    end
    -- selene: allow(incorrect_standard_library_use)
    return loadfile(ret.modpath, nil, nil, ret.stat)
  end
end

return M