local M = {}

---@class DirenvConfig
---@field bin string Path to direnv executable
---@field autoload_direnv boolean|string Automatically load direnv when opening files. true/false or "confirm" to show file first
---@field cache_ttl integer Cache TTL in milliseconds for direnv status checks
---@field statusline table Configuration for statusline integration
---@field statusline.enabled boolean Enable statusline integration
---@field statusline.icon string Icon to show in statusline
---@field keybindings table Keybindings configuration
---@field keybindings.allow string Keybinding to allow direnv
---@field keybindings.deny string Keybinding to deny direnv
---@field keybindings.reload string Keybinding to reload direnv
---@field keybindings.edit string Keybinding to edit .envrc
---@field notifications table Notification settings
---@field notifications.level integer Log level for notifications
---@field notifications.silent_autoload boolean Don't show notifications during autoload and initialization

local cache = {
   status = nil,
   path = nil,
   last_check = 0,
   pending_request = false,
}

local notification_queue = {}
local pending_callbacks = {}

---Check if an executable is available in PATH
---@param executable_name string Name of the executable
---@return boolean is_available
local function check_executable(executable_name)
   if vim.fn.executable(executable_name) ~= 1 then
      vim.notify(
         "Executable '"
            .. executable_name
            .. "' not found. Please install "
            .. executable_name
            .. " first.",
         vim.log.levels.ERROR
      )
      return false
   end
   return true
end

---Get current working directory safely
---@return string|nil cwd Current working directory or nil on error
local function get_cwd()
   local cwd_result, err = vim.uv.cwd()
   if err then
      vim.schedule(function()
         vim.notify(
            "Failed to get current directory: " .. err,
            vim.log.levels.ERROR
         )
      end)
      return nil
   end
   return cwd_result
end

---Setup keymaps for the plugin
---@param keymaps table List of keymap definitions
---@param mode string|table Vim mode for the keymap
local function setup_keymaps(keymaps, mode)
   for _, map in ipairs(keymaps) do
      local options = vim.tbl_extend(
         "force",
         { noremap = true, silent = true },
         map[3] or {}
      )
      vim.keymap.set(mode, map[1], map[2], options)
   end
end

---Safe notify function that works in both sync and async contexts
---@param msg string Message to display
---@param level? integer Log level
---@param opts? table Additional notification options
local function notify(msg, level, opts)
   -- Ensure level is an integer
   level = level
      or (M.config and M.config.notifications.level or vim.log.levels.INFO)
   opts = opts or {}
   opts = vim.tbl_extend("force", { title = "direnv.nvim" }, opts)

   if vim.in_fast_event() then
      table.insert(notification_queue, {
         msg = msg,
         level = level,
         opts = opts,
      })

      vim.schedule(function()
         while #notification_queue > 0 do
            local item = table.remove(notification_queue, 1)
            vim.notify(item.msg, item.level, item.opts)
         end
      end)
   else
      vim.notify(msg, level, opts)
   end
end

---Process any pending notifications
local function process_notification_queue()
   vim.schedule(function()
      while #notification_queue > 0 do
         local item = table.remove(notification_queue, 1)
         vim.notify(item.msg, item.level, item.opts)
      end
   end)
end

---Get current direnv status via JSON API
---@param callback function Callback function to handle result
M._get_rc_status = function(callback)
   local loop = vim.uv or vim.loop
   local now = math.floor(loop.hrtime() / 1000000) -- ns -> ms
   local ttl = (M.config and M.config.cache_ttl) or 5000

   if cache.status ~= nil and (now - cache.last_check) < ttl then
      return callback(cache.status, cache.path)
   end

   table.insert(pending_callbacks, callback)

   if cache.pending_request then
      return
   end

   cache.pending_request = true

   local cwd = get_cwd()
   if not cwd then
      cache.pending_request = false
      for _, cb in ipairs(pending_callbacks) do
         cb(nil, nil)
      end
      pending_callbacks = {}
      return
   end

   local on_exit = function(obj)
      cache.pending_request = false

      if obj.code ~= 0 then
         vim.schedule(function()
            notify(
               "Failed to get direnv status: "
                  .. (obj.stderr or "unknown error"),
               vim.log.levels.ERROR
            )
         end)
         for _, cb in ipairs(pending_callbacks) do
            cb(nil, nil)
         end
         pending_callbacks = {}
         return
      end

      local ok, status = pcall(vim.json.decode, obj.stdout)
      if not ok or not status or not status.state then
         for _, cb in ipairs(pending_callbacks) do
            cb(nil, nil)
         end
         pending_callbacks = {}
         return
      end

      if status.state.foundRC == vim.NIL then
         cache.status = nil
         cache.path = nil
         cache.last_check = now
         for _, cb in ipairs(pending_callbacks) do
            cb(nil, nil)
         end
         pending_callbacks = {}
         return
      end

      cache.status = status.state.foundRC.allowed
      cache.path = status.state.foundRC.path
      cache.last_check = now

      for _, cb in ipairs(pending_callbacks) do
         cb(status.state.foundRC.allowed, status.state.foundRC.path)
      end
      pending_callbacks = {}
   end

   vim.system(
      { M.config.bin, "status", "--json" },
      { text = true, cwd = cwd },
      on_exit
   )
end

---Initialize direnv for current directory
---@param path string Path to .envrc file
M._init = function(path)
   local cwd = vim.fs.dirname(path)
   local silent = M.config.notifications.silent_autoload
      and vim.b.direnv_autoload_triggered

   if not silent then
      vim.schedule(function()
         notify("Loading environment from " .. path, vim.log.levels.INFO)
      end)
   end

   local on_exit = function(obj)
      if obj.code ~= 0 then
         vim.schedule(function()
            notify(
               "Failed to load direnv: " .. (obj.stderr or "unknown error"),
               vim.log.levels.ERROR
            )
         end)
         return
      end

      vim.schedule(function()
         local env_commands = vim.split(obj.stdout, "\n")
         if #env_commands > 0 then
            for _, cmd in ipairs(env_commands) do
               if cmd ~= "" then
                  pcall(function()
                     vim.cmd(cmd)
                  end)
               end
            end

            if not silent then
               notify(
                  "direnv environment loaded successfully",
                  vim.log.levels.INFO
               )
            end
            vim.api.nvim_exec_autocmds(
               "User",
               { pattern = "DirenvLoaded", modeline = false }
            )
         end
      end)
   end

   vim.system(
      { M.config.bin, "export", "vim" },
      { text = true, cwd = cwd },
      on_exit
   )
end

---Allow direnv for current directory
M.allow_direnv = function()
   M._get_rc_status(function(_, path)
      if not path then
         vim.schedule(function()
            notify(
               "No .envrc file found in current directory",
               vim.log.levels.WARN
            )
         end)
         return
      end

      vim.schedule(function()
         notify("Allowing direnv for " .. path, vim.log.levels.INFO)
      end)

      -- Capture dir before the async call
      local cwd = get_cwd()
      if not cwd then
         return
      end

      vim.system(
         { M.config.bin, "allow" },
         { text = true, cwd = cwd },
         function(obj)
            if obj.code ~= 0 then
               vim.schedule(function()
                  notify(
                     "Failed to allow direnv: " .. (obj.stderr or ""),
                     vim.log.levels.ERROR
                  )
               end)
               return
            end

            -- Clear cache to ensure we get fresh data
            -- and then load the environment
            cache.status = nil
            M.check_direnv()

            vim.schedule(function()
               notify("direnv allowed for " .. path, vim.log.levels.INFO)
            end)
         end
      )
   end)
end

---Deny direnv for current directory
M.deny_direnv = function()
   M._get_rc_status(function(_, path)
      if not path then
         vim.schedule(function()
            notify(
               "No .envrc file found in current directory",
               vim.log.levels.WARN
            )
         end)
         return
      end

      vim.schedule(function()
         notify("Denying direnv for " .. path, vim.log.levels.INFO)
      end)

      local cwd = get_cwd()
      if not cwd then
         return
      end

      vim.system(
         { M.config.bin, "deny" },
         { text = true, cwd = cwd },
         function(obj)
            if obj.code ~= 0 then
               vim.schedule(function()
                  notify(
                     "Failed to deny direnv: " .. (obj.stderr or ""),
                     vim.log.levels.ERROR
                  )
               end)
               return
            end

            cache.status = nil

            vim.schedule(function()
               notify("direnv denied for " .. path, vim.log.levels.INFO)
            end)
         end
      )
   end)
end

---Edit the .envrc file
M.edit_envrc = function()
   M._get_rc_status(function(_, path)
      if not path then
         -- TODO: envrc can be in a different directory, e.g., the parent.
         -- We should search for it backwards eventually.
         local cwd = get_cwd()
         if not cwd then
            return
         end

         local envrc_path = cwd .. "/.envrc"
         vim.schedule(function()
            local create_new = vim.fn.confirm(
               "No .envrc file found. Create one?",
               "&Yes\n&No",
               1
            )

            if create_new == 1 then
               vim.cmd("edit " .. envrc_path)
            end
         end)
         return
      end

      vim.schedule(function()
         vim.cmd("edit " .. path)
      end)
   end)
end

---Check and load direnv if applicable
M.check_direnv = function()
   local on_exit = function(status, path)
      if status == nil or path == nil then
         return
      end

      -- Status 0 means the .envrc file is allowed
      if status == 0 then
         return M._init(path)
      end

      -- Status 2 means the .envrc file is explicitly blocked
      if status == 2 then
         vim.schedule(function()
            notify(
               path .. " is explicitly blocked by direnv",
               vim.log.levels.WARN
            )
         end)
         return
      end

      -- Status 1 means the .envrc file needs approval
      if M.config.autoload_direnv == "confirm" then
         vim.schedule(function()
            vim.cmd("edit " .. path)
            vim.defer_fn(function()
               local choice = vim.fn.confirm(
                  "Load environment from " .. path .. "?",
                  "&Yes\n&No",
                  1
               )
               if choice == 1 then
                  M.allow_direnv()
               end
            end, 100)
         end)
      else
         vim.schedule(function()
            local choice = vim.fn.confirm(
               path .. " is not allowed by direnv. What would you like to do?",
               "&Allow\n&Block\n&Ignore",
               1
            )

            if choice == 1 then
               M.allow_direnv()
            elseif choice == 2 then
               M.deny_direnv()
            end
            -- Ignore means do nothing
         end)
      end
   end

   M._get_rc_status(on_exit)
end

---Get direnv status for statusline integration
---@return string status_string
M.statusline = function()
   if not M.config.statusline.enabled then
      return ""
   end

   if cache.status == 0 then
      return M.config.statusline.icon .. " active"
   elseif cache.status == 1 then
      return M.config.statusline.icon .. " pending"
   elseif cache.status == 2 then
      return M.config.statusline.icon .. " blocked"
   else
      return ""
   end
end

---Setup the plugin with user configuration
---@param user_config? table User configuration table
M.setup = function(user_config)
   M.config = vim.tbl_deep_extend("force", {
      bin = "direnv",
      autoload_direnv = false,
      cache_ttl = 5000,
      statusline = {
         enabled = false,
         icon = "󱚟",
      },
      keybindings = {
         allow = "<Leader>da",
         deny = "<Leader>dd",
         reload = "<Leader>dr",
         edit = "<Leader>de",
      },
      notifications = {
         level = vim.log.levels.INFO,
         silent_autoload = true,
      },
   }, user_config or {})

   if not check_executable(M.config.bin) then
      return
   end

   -- Create user commands
   vim.api.nvim_create_user_command("Direnv", function(opts)
      local cmds = {
         ["allow"] = M.allow_direnv,
         ["deny"] = M.deny_direnv,
         ["reload"] = M.check_direnv,
         ["edit"] = M.edit_envrc,
         ["status"] = function()
            M._get_rc_status(function(status, path)
               if not path then
                  vim.schedule(function()
                     notify(
                        "No .envrc file found in current directory",
                        vim.log.levels.INFO
                     )
                  end)
                  return
               end

               local status_text = (status == 0 and "allowed")
                  or (status == 1 and "pending")
                  or (status == 2 and "blocked")
                  or "unknown"

               vim.schedule(function()
                  notify(
                     "direnv status: " .. status_text .. " for " .. path,
                     vim.log.levels.INFO
                  )
               end)
            end)
         end,
      }

      local cmd = cmds[string.lower(opts.fargs[1])]
      if cmd then
         cmd()
      else
         notify(
            "Unknown direnv command: " .. opts.fargs[1],
            vim.log.levels.ERROR
         )
      end
   end, {
      nargs = 1,
      complete = function()
         return { "allow", "deny", "reload", "edit", "status" }
      end,
   })

   -- Setup keybindings
   setup_keymaps({
      {
         M.config.keybindings.allow,
         function()
            M.allow_direnv()
         end,
         { desc = "Allow direnv" },
      },
      {
         M.config.keybindings.deny,
         function()
            M.deny_direnv()
         end,
         { desc = "Deny direnv" },
      },
      {
         M.config.keybindings.reload,
         function()
            M.check_direnv()
         end,
         { desc = "Reload direnv" },
      },
      {
         M.config.keybindings.edit,
         function()
            M.edit_envrc()
         end,
         { desc = "Edit .envrc file" },
      },
   }, "n")

   -- Check for .envrc files and set up autoload
   local group_id = vim.api.nvim_create_augroup("DirenvNvim", { clear = true })

   if M.config.autoload_direnv then
      -- Check on directory change
      vim.api.nvim_create_autocmd({ "DirChanged" }, {
         group = group_id,
         callback = function()
            vim.b.direnv_autoload_triggered = true
            M.check_direnv()
            vim.defer_fn(function()
               vim.b.direnv_autoload_triggered = false
            end, 1000)
         end,
      })

      -- Check on startup if we're in a directory with .envrc
      vim.api.nvim_create_autocmd({ "VimEnter" }, {
         group = group_id,
         callback = function()
            vim.b.direnv_autoload_triggered = true
            M.check_direnv()
            -- Reset the flag after a short delay
            vim.defer_fn(function()
               vim.b.direnv_autoload_triggered = false
            end, 1000)
         end,
         once = true,
      })
   end

   -- Check for .envrc changes
   vim.api.nvim_create_autocmd({ "BufWritePost" }, {
      pattern = ".envrc",
      group = group_id,
      callback = function()
         cache.status = nil
         notify(
            ".envrc file changed. Run :Direnv allow to activate changes.",
            vim.log.levels.INFO
         )
      end,
   })

   -- Expose a command to refresh the statusline value without triggering reload
   vim.api.nvim_create_user_command("DirenvStatuslineRefresh", function()
      cache.last_check = 0
      M._get_rc_status(function() end)
   end, {})

   M._get_rc_status(function() end)

   process_notification_queue()

   if not M.config.notifications.silent_autoload then
      notify("direnv.nvim initialized", vim.log.levels.DEBUG)
   end
end

return M