local util = require "navigator.util"
local log = util.log
local trace = util.trace
local api = vim.api
local references = {}
_NG_hi_list = {}
_NG_current_symbol = ""
_NG_ref_hi_idx = 1

-- extract symbol from cursor
local function get_symbol()
  local currentWord = vim.fn.expand('<cword>')
  return currentWord
end

local function add_locs(bufnr, result)
  local symbol = get_symbol()
  if #result < 1 then
    return
  end
  symbol = string.format("%s_%i_%i_%i", symbol, bufnr, result[1].range.start.line,
                         result[1].range.start.character)
  if _NG_hi_list[symbol] == nil then
    _NG_hi_list[symbol] = {range = {}}
  end
  if _NG_hi_list[symbol] ~= nil then
    log("already added", symbol)
    _NG_hi_list[symbol].range = {}
    -- vim.fn.matchdelete(hid)
  end
  trace("add ", symbol)
  _NG_hi_list[symbol].range = result
  _NG_current_symbol = symbol
end

local function nohl()
  for key, value in pairs(_NG_hi_list) do
    if value.hi_ids ~= nil then
      for _, v in ipairs(value.hi_ids) do
        log("delete", v)
        vim.fn.matchdelete(v)
      end
      _NG_hi_list[key].hi_ids = nil
    end
  end
end

local function hi_symbol()
  local symbol_wd = get_symbol()
  local symbol = _NG_current_symbol
  if string.find(symbol, symbol_wd) == nil then
    vim.lsp.buf.document_highlight()
    symbol = _NG_current_symbol
  end
  if symbol == nil or symbol == "" then
    log("nil symbol")
    return
  end

  _NG_ref_hi_idx = _NG_ref_hi_idx + 1
  if _NG_ref_hi_idx > 6 then --  6 magic number for colors
    _NG_ref_hi_idx = 1
  end

  local range = _NG_hi_list[symbol].range or {}
  if _NG_hi_list[symbol].hi_ids ~= nil then
    for _, value in ipairs(_NG_hi_list[symbol].hi_ids) do
      log("delete", value)
      vim.fn.matchdelete(value)
    end
    _NG_hi_list[symbol].hi_ids = nil
    return
  end
  local cur_pos = vim.fn.getpos('.')
  _NG_hi_list[symbol].hi_ids = {}
  local totalref = #range
  local cmd = string.format("%s/\\<%s\\>//gn", "%s", symbol_wd)
  local total_match = 0
  local match_result = vim.api.nvim_exec(cmd, true)
  local p = match_result:find(" match")
  vim.cmd("nohl")
  vim.fn.setpos('.', cur_pos)
  if p ~= nil then
    p = match_result:sub(1, p)
    total_match = tonumber(p)
  end
  if total_match == totalref then -- same number as matchpos
    log(total_match, "use matchadd()")
    local k = range[1].kind
    local hi_name = string.format("NGHiReference_%i_%i", _NG_ref_hi_idx, k)
    local m = string.format("\\<%s\\>", symbol_wd)
    local r = vim.fn.matchadd(hi_name, m, 20)
    trace("hi id", m, hi_name, r)
    table.insert(_NG_hi_list[symbol].hi_ids, r)
    --
    -- vim.fn.matchdelete(r)
  else
    for _, value in ipairs(range) do
      local k = value.kind
      local l = value.range.start.line + 1
      local el = value.range['end'].line + 1

      local cs = value.range.start.character + 1
      local ecs = value.range['end'].character + 1
      if el ~= l and cs == 1 and ecs > 1 then
        l = el
      end
      local w = value.range['end'].character - value.range.start.character
      local hi_name = string.format("NGHiReference_%i_%i", _NG_ref_hi_idx, k)
      log(hi_name, {l, cs, w})
      local m = vim.fn.matchaddpos(hi_name, {{l, cs, w}}, 10)
      table.insert(_NG_hi_list[symbol].hi_ids, m)
    end
  end

  -- clean the _NG_hi_list
  for key, value in pairs(_NG_hi_list) do
    if value.hi_ids == nil then
      _NG_hi_list[key] = nil
    end
  end

  -- log(_NG_hi_list)
end

-- returns r1 < r2 based on start of range
local function before(r1, r2)
  if r1.start.line < r2.start.line then
    return true
  end
  if r2.start.line < r1.start.line then
    return false
  end
  if r1.start.character < r2.start.character then
    return true
  end
  return false
end

local function handle_document_highlight(_, _, result, _, bufnr, _)
  if not bufnr then
    return
  end
  if type(result) ~= "table" then
    vim.lsp.util.buf_clear_references(bufnr)
    return
  end

  table.sort(result, function(a, b)
    return before(a.range, b.range)
  end)
  references[bufnr] = result
end
-- modify from vim-illuminate
local function goto_adjent_reference(opt)
  log(opt)
  opt = vim.tbl_extend("force", {forward = true, wrap = true}, opt or {})

  local bufnr = vim.api.nvim_get_current_buf()
  local refs = references[bufnr]
  if not refs or #refs == 0 then
    return nil
  end

  local next = nil
  local nexti = nil
  local crow, ccol = unpack(vim.api.nvim_win_get_cursor(0))
  local crange = {start = {line = crow - 1, character = ccol}}

  for i, ref in ipairs(refs) do
    local range = ref.range
    if opt.forward then
      if before(crange, range) and (not next or before(range, next)) then
        next = range
        nexti = i
      end
    else
      if before(range, crange) and (not next or before(next, range)) then
        next = range
        nexti = i
      end
      log(nexti, next)
    end
  end
  if not next and opt.wrap then
    nexti = opt.reverse and #refs or 1
    next = refs[nexti].range
  end

  log(next)
  vim.api.nvim_win_set_cursor(0, {next.start.line + 1, next.start.character})
  return next
end

local function cmd_nohl()
  local cl = vim.trim(vim.fn.getcmdline())
  if #cl > 3 and ('nohlsearch'):match(cl) then
    vim.schedule(nohl)
  end
end

local function documentHighlight()
  api.nvim_exec([[
      autocmd ColorScheme * |
        hi default LspReferenceRead cterm=bold gui=Bold ctermbg=yellow guifg=yellow guibg=purple4 |
        hi default LspReferenceText cterm=bold gui=Bold ctermbg=red guifg=SlateBlue guibg=MidnightBlue |
        hi default LspReferenceWrite cterm=bold gui=Bold,Italic ctermbg=red guifg=DarkSlateBlue guibg=MistyRose

      augroup lsp_document_highlight
        autocmd! * <buffer>
        autocmd CursorHold <buffer> lua vim.lsp.buf.document_highlight()
        autocmd CursorMoved <buffer> lua vim.lsp.buf.clear_references()
      augroup END
    ]], false)
  vim.lsp.handlers["textDocument/documentHighlight"] =
      function(err, _, result, _, bufnr)
        if err then
          print(err)
          return
        end
        if not result then
          return
        end
        trace("dochl", result)
        bufnr = api.nvim_get_current_buf()
        vim.lsp.util.buf_clear_references(bufnr)
        vim.lsp.util.buf_highlight_references(bufnr, result)
        bufnr = bufnr or 0
        if type(result) ~= "table" then
          vim.lsp.util.buf_clear_references(bufnr)
          return
        end
        table.sort(result, function(a, b)
          return before(a.range, b.range)
        end)
        references[bufnr] = result
        add_locs(bufnr, result)
      end
end

return {
  documentHighlight = documentHighlight,
  goto_adjent_reference = goto_adjent_reference,
  handle_document_highlight = handle_document_highlight,
  hi_symbol = hi_symbol,
  nohl = nohl,
  cmd_nohl = cmd_nohl
}