local util = require('navigator.util')
local log = util.log
local trace = util.trace
local mk_handler = util.mk_handler
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()
  return vim.fn.expand('<cword>')
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
    trace('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
        trace('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
    trace(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)
      trace(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 not r1 or not r2 then
    return false
  end
  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 handle_document_highlight = mk_handler(function(_, result, ctx)
  trace(result, ctx)
  if not ctx.bufnr then
    log('ducment highlight error', result, ctx)
    return
  end
  if type(result) ~= 'table' or vim.fn.empty(result) == 1 then
    log('clear up', result)
    vim.lsp.util.buf_clear_references(ctx.bufnr)
    return
  end

  table.sort(result, function(a, b)
    return before(a.range, b.range)
  end)
  references[ctx.bufnr] = result
  local client_id = ctx.client_id
  vim.lsp.util.buf_highlight_references(ctx.bufnr, result, util.encoding(client_id))
end)
-- modify from vim-illuminate
local function goto_adjent_reference(opt)
  trace(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

  trace(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

_G.nav_doc_hl = function()
  local bufnr = vim.api.nvim_get_current_buf()
  local ref_params = vim.lsp.util.make_position_params()
  vim.lsp.for_each_buffer_client(bufnr, function(client, client_id, bufnr)
    if client.resolved_capabilities.document_highlight then
      client.request('textDocument/documentHighlight', ref_params, handle_document_highlight, bufnr)
    end
  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 nav_doc_hl()
        autocmd CursorMoved <buffer> lua vim.lsp.buf.clear_references()
      augroup END
    ]],
    false
  )
  vim.lsp.handlers['textDocument/documentHighlight'] = mk_handler(function(err, result, ctx)
    local bufnr = ctx.bufnr or api.nvim_get_current_buf()
    if err then
      vim.notify(err, vim.lsp.log_levels.ERROR)
      return
    end
    if not result or not result[1] or not result[1]['range'] then
      return
    end
    trace('dochl', result)
    bufnr = bufnr or 0
    if type(result) ~= 'table' then
      vim.lsp.util.buf_clear_references(bufnr)
      return
    end
    local client_id = ctx.client_id
    vim.lsp.util.buf_clear_references(bufnr)
    vim.lsp.util.buf_highlight_references(bufnr, result, util.encoding(client_id))
    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,
}