--
-- Surround: add, change, and delete surrounding characters (quotes, brackets, HTML tags).
--
-- Mappings:
--   ys{motion}{char} - add surround (e.g., ysiw" surrounds word with quotes)
--   cs{from}{to}     - change surround (e.g., cs"' changes " to ')
--   ds{char}         - delete surround (e.g., ds" removes surrounding quotes)
--   S{char}          - surround visual selection
--
local Range = require('u').Range
local vim_repeat = require('u').repeat_

local M = {}

local ESC = vim.api.nvim_replace_termcodes('<Esc>', true, false, true)

local surrounds = {
  [')'] = { left = '(', right = ')' },
  ['('] = { left = '( ', right = ' )' },
  [']'] = { left = '[', right = ']' },
  ['['] = { left = '[ ', right = ' ]' },
  ['}'] = { left = '{', right = '}' },
  ['{'] = { left = '{ ', right = ' }' },
  ['>'] = { left = '<', right = '>' },
  ['<'] = { left = '< ', right = ' >' },
  ["'"] = { left = "'", right = "'" },
  ['"'] = { left = '"', right = '"' },
  ['`'] = { left = '`', right = '`' },
}

--- @type { left: string, right: string } | nil
local CACHED_BOUNDS = nil

--- @return { left: string, right: string }|nil
local function prompt_for_bounds()
  if vim_repeat.is_repeating() then return CACHED_BOUNDS end

  local cn = vim.fn.getchar()
  if type(cn) ~= 'number' or cn < 32 or cn > 126 then return end
  local c = vim.fn.nr2char(cn)

  if c == '<' then
    vim.keymap.set('c', '>', '><CR>')
    local tag = '<' .. vim.fn.input '<'
    if tag == '<' then return end
    vim.keymap.del('c', '>')
    local endtag = '</' .. tag:sub(2):match '[^ >]*' .. '>'
    CACHED_BOUNDS = { left = tag, right = endtag }
    return CACHED_BOUNDS
  else
    CACHED_BOUNDS = surrounds[c] or { left = c, right = c }
    return CACHED_BOUNDS
  end
end

--- @param range u.Range
--- @param bounds { left: string, right: string }
local function do_surround(range, bounds)
  local left = bounds.left
  local right = bounds.right
  if range.mode == 'V' then
    left = vim.trim(left)
    right = vim.trim(right)
  end

  if range.mode == 'v' then
    range:replace(left .. range:text() .. right)
  elseif range.mode == 'V' then
    local bufnr = vim.api.nvim_get_current_buf()
    local first_line = Range.from_line(bufnr, range.start.lnum):text()
    local ws = first_line:match '^%s*'
    local expandtab = vim.bo[bufnr].expandtab
    local shiftwidth = vim.bo[bufnr].shiftwidth

    local indent_str, base_indent
    if expandtab then
      indent_str = string.rep(' ', shiftwidth)
      base_indent = math.floor(#ws / shiftwidth)
    else
      indent_str = '\t'
      base_indent = #ws
    end

    local lines = {}
    local function write(line, indent_offset)
      table.insert(lines, indent_str:rep(base_indent + (indent_offset or 0)) .. line)
    end

    write(left)
    local indent_prefix = indent_str:rep(base_indent)
    for _, line in ipairs(range:lines()) do
      if line:sub(1, #indent_prefix) == indent_prefix then line = line:sub(#indent_prefix + 1) end
      write(line, 1)
    end
    write(right)

    range:replace(lines)
  end

  range.start:save_to_pos '.'
end

-- Add surround:
--- @param ty 'line' | 'char' | 'block'
function _G.MySurroundOpFunc(ty)
  if ty == 'block' then
    -- We won't handle block-selection:
    return
  end

  local range = Range.from_op_func(ty)
  local hl
  if not vim_repeat.is_repeating() then hl = range:highlight('IncSearch', { priority = 999 }) end

  local bounds = prompt_for_bounds()
  if hl then hl.clear() end
  if bounds == nil then return end

  do_surround(range, bounds)
end

function M.setup()
  require('u.repeat').setup()

  -- Visual
  vim.keymap.set('x', 'S', function()
    local range = Range.from_vtext()
    local bounds = prompt_for_bounds()
    if bounds == nil then return end

    do_surround(range, bounds)
    -- this is a visual mapping: end in normal mode:
    vim.cmd.normal(ESC)
  end, { noremap = true, silent = true })

  -- Change
  vim.keymap.set('n', 'cs', function()
    local from_cn = vim.fn.getchar() --[[@as number]]
    -- Check for non-printable characters:
    if from_cn < 32 or from_cn > 126 then return end

    vim_repeat.run_repeatable(function()
      local from_c = vim.fn.nr2char(from_cn)
      local from = surrounds[from_c] or { left = from_c, right = from_c }
      local function get_fresh_arange()
        local arange = Range.from_motion('a' .. from_c, { user_defined = true })
        if arange == nil then return end
        if from_c == 'q' then
          from.left = arange.start:char()
          from.right = arange.stop:char()
        end
        return arange
      end

      local arange = get_fresh_arange()
      if arange == nil then return end

      local hl_info1 = vim_repeat.is_repeating() and nil
        or Range.new(arange.start, arange.start, 'v'):highlight('IncSearch', { priority = 999 })
      local hl_info2 = vim_repeat.is_repeating() and nil
        or Range.new(arange.stop, arange.stop, 'v'):highlight('IncSearch', { priority = 999 })
      local hl_clear = function()
        if hl_info1 then hl_info1.clear() end
        if hl_info2 then hl_info2.clear() end
      end

      local to = prompt_for_bounds()
      hl_clear()
      if to == nil then return end

      if from_c == 't' then
        -- For tags, we want to replace the inner text, not the tag:
        local irange = Range.from_motion('i' .. from_c, { user_defined = true })
        if arange == nil or irange == nil then return end

        local lrange, rrange = arange:difference(irange)
        if not lrange or not rrange then return end

        rrange:replace(to.right)
        lrange:replace(to.left)
      else
        -- replace `from.right` with `to.right`:
        local right_text = arange:sub(-1, -#from.right)
        right_text:replace(to.right)

        -- replace `from.left` with `to.left`:
        local left_text = arange:sub(1, #from.left)
        left_text:replace(to.left)
      end
    end)
  end, { noremap = true, silent = true })

  -- Delete
  local CACHED_DELETE_FROM = nil
  vim.keymap.set('n', 'ds', function()
    vim_repeat.run_repeatable(function()
      local txt_obj = vim_repeat.is_repeating() and CACHED_DELETE_FROM or vim.fn.getcharstr()
      CACHED_DELETE_FROM = txt_obj

      local bufnr = vim.api.nvim_get_current_buf()
      local irange = Range.from_motion('i' .. txt_obj)
      local arange = Range.from_motion('a' .. txt_obj)
      if arange == nil or irange == nil then return end
      local starting_cursor_pos = arange.start:clone()

      -- Now, replace `arange` with the content of `irange`.  If `arange` was multiple lines,
      -- dedent the contents first, and operate in linewise mode
      if arange.start.lnum ~= arange.stop.lnum then
        -- Auto dedent:
        vim.cmd.normal('<i' .. vim.trim(txt_obj))
        -- Dedenting moves the cursor, so we need to set the cursor to a consistent starting spot:
        arange.start:save_to_pos '.'
        -- Dedenting also changed the inner text, so re-acquire it:
        arange = Range.from_motion('a' .. txt_obj)
        irange = Range.from_motion('i' .. txt_obj)
        if arange == nil or irange == nil then return end -- should never be true
        arange:replace(irange:lines())
        -- `arange:replace(..)` updates its own `stop` position, so we will use
        -- `arange` as the final resulting range that holds the modified text

        -- delete last line, if it is empty:
        local last = Range.from_line(bufnr, arange.stop.lnum)
        if last:text():match '^%s*$' then last:replace(nil) end

        -- delete first line, if it is empty:
        local first = Range.from_line(bufnr, arange.start.lnum)
        if first:text():match '^%s*$' then first:replace(nil) end
      else
        -- trim start:
        irange = irange:trim_start():trim_stop()
        arange:replace(irange:lines())
      end

      starting_cursor_pos:save_to_pos '.'
    end)
  end, { noremap = true, silent = true })

  vim.keymap.set('n', 'ys', function()
    vim.o.operatorfunc = 'v:lua.MySurroundOpFunc'
    return 'g@'
  end, { expr = true })
end

return M