local popup = require'plenary.popup'
local utils = require'presser.utils'
local gcm = require('presser.context_manager')

local api = vim.api

local presser = {}  -- list of functions to be exported


-- :@Dev: close all Presser windows that may be open for all contexts
presser.close = function ()
  gcm.flush() -- invoke the context manager to flush the table
end


-- @Description: Construct a new instance of a window and buffer using the 'plenary.popup' module.
-- @Params:
--    + `_type` ~ string denoting which context manager is owner of the window.
--    + `placeholder` ~ string allowing for placeholder text to be placed within the buffer when constructed.
--    + `opts` ~ a table of additional options to be provided when constructing the window.
-- @Returns: nil. Constructs a new window and stores the window's ID in a global table.
--
-- @Dev: This function is to be as generic for creating a window whilst allowing for as much customisation over the
-- window/buffer which are to be constructed. Users are to access this function so is not part of the module export.
-- However, it's used by all internal built-ins which are meant to be used by users. Consider a class constructor in
-- C++, this function is akin to that behaviour and is responsible for constructing the window/buffer and ensuring it
-- can be tracked by Vim itself.
local new = function ( _ctx, label, opts )
  local opts = opts or {}
  if not opts.placeholder then
    opts["placeholder"] = ""
  end
  
  local buf_opts = {
    minwidth = 80, -- getwin_w() / 2 - ((getwin_w() % 2) / 2),
    borderchars = { "─", "│", "─", "│", "╭", "╮", "╯", "╰" },
  }

  if opts.window then
    for k,v in pairs( opts.window ) do
      buf_opts[k] = v
    end
  end

  local obj = popup.create( opts.placeholder, buf_opts )
  gcm.update( _ctx, { id = obj, what = label, allowed = opts.allowed } )
  -- :TODO: call update function in context manager
--  table.insert( manager[_type], obj )
--  g.presser_buf_ctx = manager

  -- :@Dev: handle for keybindings (TODO: any future stuff below here once window is made)
  local buf_id = function ()
    return api.nvim_win_get_buf(obj)
  end

  -- handle for key bindings
  if opts.keybinds then
    for mode, mode_map in pairs( opts.keybinds ) do
      mode = string.lower(mode)

      for key_bind, key_action in pairs(mode_map) do
        local key_bind = api.nvim_replace_termcodes(key_bind, true, false, true),
        api.nvim_buf_set_keymap(buf_id(), mode, key_bind, key_action,
          { noremap = true, silent = true }
        )
      end
    end
  end
end


presser.move_next_buffer = function ()
  local ctxs = 0
  local c = vim.g.presser_buf_ctx
  local buf = api.nvim_get_current_buf()

  for _, v in pairs( c ) do for idx, _ in pairs( v ) do ctxs = idx end end

  for ctx, ctx_obj in pairs( c ) do 
    for idx, obj in pairs( ctx_obj ) do 
      if api.nvim_win_get_buf( obj.id ) == buf then
        -- get the next window, and put cursor there
        local s = idx
        repeat
          local win = ctx_obj[(idx % ctxs) + 1]
          if win.allowed then
            api.nvim_set_current_win( ctx_obj[(idx % ctxs) + 1].id )
            break
          end
          idx = (idx % ctxs) + 1
        until s == idx
      end
    end
  end
end


local read_buffer = function ()
  local c = vim.g.presser_buf_ctx

  local b = {}
  for ctx, ctx_obj in pairs( c ) do 
    for idx, obj in pairs( ctx_obj ) do 
      if obj.allowed then
        local buf = api.nvim_win_get_buf( obj.id )
        table.insert(b, utils.clean_buf( api.nvim_buf_get_lines( buf, 0, -1, false )[1] ))
      end
    end
  end

  return b
end

presser.execute = function ()
  local result = read_buffer()
  presser.close()

  local cmd = ":%s/" .. result[1] .. "/" .. result[2] .. "/g"
  api.nvim_exec( cmd, false )
end


local start_buffer = function ( label )
  for ctx, ctx_obj in pairs( vim.g.presser_buf_ctx ) do 
    for idx, record in pairs( ctx_obj ) do 
      if record.what == label then
        api.nvim_set_current_win( record.id )
      end
    end
  end
end


-- @Description: Find and replace words within the current buffer.
-- @Params:
-- @Returns: nil.
--
-- @Dev: function is responsible to creating all required buffers to allow full user interaction.
--
-- @Future: implementation may allow for greater user customisation similar to what's found with
-- extensions such as Telescope. For now, it should provide a concrete UI for purpose of design.
function presser.find_replace()
  -- define the context which these windows will belong to in the context manager.
  local ctx = "find_replace"
  gcm.create( ctx )
  
  local keymap = {
    n = {
      ["<esc>"] = "<cmd>lua require'presser'.close()<CR>",
      ["<A-a>"] = "<cmd>lua require'presser'.execute()<CR>",
    },
    i = {
      ["<Tab>"] = "<cmd>lua require'presser'.move_next_buffer()<CR>",
      ["<A-a>"] = "<cmd>lua require'presser'.execute()<CR>",
    }
  }

  -- get the centre of the current buffer
  local c_cols = math.floor( api.nvim_win_get_width(0) / 2 )
  local c_lines = math.floor( api.nvim_win_get_height(0) / 2 )

-- print(c_cols, c_lines)

  -- options for the title buffer of the built-in
  local opts = {
    placeholder = "Find & Replace",
    allowed = false,
    window = {
      line = c_lines - 3,
      border = false,
      minwidth = 82,
      padding = { 0, 1, 1, 1 }
    },
  }
  local tab_title = new( ctx, "presser_fr_title", opts )

  -- options for the replace buffer
  local opts = {
    window = {
      line = c_lines,
      title = "Find",
    },
    keybinds = keymap,
  }
  local find = new ( ctx, "find_buf", opts )

  -- modify options for find buffer
  opts["window"]["line"] = c_lines+3
  opts["window"]["title"] = "Replace"
  local replace = new( ctx, "replace_buf", opts )

  local result = start_buffer( "find_buf" )
  api.nvim_feedkeys('A', 'n', false)
end

--presser.find_replace()

return presser