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

---@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 = {}

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()

  -- 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
        break
      end
    end
    Util.track()
  end
  Config.mapleader = vim.g.mapleader

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

  -- setup handlers
  Util.track("handlers")
  Handler.setup()
  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
    if not (plugin._.installed or Plugin.has_errors(plugin)) then
      for _, colorscheme in ipairs(Config.options.install.colorscheme) do
        M.colorscheme(colorscheme)
        if vim.g.colors_name or pcall(vim.cmd.colorscheme, colorscheme) then
          break
        end
      end
      require("lazy.manage").install({ wait = true, lockfile = true })
      -- remove and 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()

  -- 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
      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

function M.get_start_plugins()
  ---@type LazyPlugin[]
  local start = {}
  for _, plugin in pairs(Config.plugins) do
    if plugin.lazy == false and not plugin._.loaded 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)[]

  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
        plugin = nil
      else
        Util.error("Plugin " .. plugin .. " not found")
        plugin = nil
      end
    end
    if plugin and not plugin._.loaded then
      M._load(plugin, reason, opts)
    end
  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)

  -- 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
function M.reload(plugin)
  M.deactivate(plugin)
  local load = false -- plugin._.loaded ~= nil

  -- 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

  for _, event in ipairs(plugin.event or {}) do
    if event == "VimEnter" or event == "UIEnter" or event:find("VeryLazy") then
      load = true
      break
    end
  end

  if load then
    M.load(plugin, { start = "reload" })
  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

  local cond = plugin.cond
  if cond == nil then
    cond = Config.options.defaults.cond
  end
  if cond ~= nil and not (opts and opts.force) then
    if cond == false or (type(cond) == "function" and not cond(plugin)) then
      plugin._.cond = false
      return
    end
  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.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 = "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
  local normname = Util.normname(plugin.name)
  ---@type string[]
  local mods = {}
  for modname, _ in pairs(Cache.lsmod(plugin.dir)) do
    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

  local is_win = jit.os:find("Windows")

  for i, path in ipairs(rtp) do
    if 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.loop.fs_stat(after) then
    table.insert(rtp, idx_after or (#rtp + 1), after)
  end

  vim.opt.rtp = rtp
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.loop.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)
  if plugin and modpath:find(plugin.dir, 1, true) == 1 then
    -- don't load if we're loading specs or if the plugin is already loaded
    if 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
    return true
  end
  return false
end

---@param modname string
function M.loader(modname)
  local paths = Util.get_unloaded_rtp(modname)
  local modpath, hash = Cache._Cache.find(modname, { rtp = false, paths = paths })
  if modpath then
    M.auto_load(modname, modpath)
    local mod = package.loaded[modname]
    if type(mod) == "table" then
      return function()
        return mod
      end
    end
    return Cache.load(modpath, { hash = hash })
  end
end

return M