refactor: massive file restructure

lua/cp/setup/navigation.lua

@@ -0,0 +1,63 @@
+local M = {}
+
+local cache = require('cp.cache')
+local logger = require('cp.log')
+local state = require('cp.state')
+
+local function get_current_problem()
+  local filename = vim.fn.expand('%:t:r')
+  if filename == '' then
+    logger.log('no file open', vim.log.levels.ERROR)
+    return nil
+  end
+  return filename
+end
+
+function M.navigate_problem(delta, language)
+  cache.load()
+  local contest_data = cache.get_contest_data(state.get_platform(), state.get_contest_id())
+  if not contest_data or not contest_data.problems then
+    logger.log(
+      'no contest metadata found. set up a problem first to cache contest data',
+      vim.log.levels.ERROR
+    )
+    return
+  end
+
+  local problems = contest_data.problems
+  local current_problem_id = state.get_problem_id()
+
+  if not current_problem_id then
+    logger.log('no current problem set', vim.log.levels.ERROR)
+    return
+  end
+
+  local current_index = nil
+  for i, prob in ipairs(problems) do
+    if prob.id == current_problem_id then
+      current_index = i
+      break
+    end
+  end
+
+  if not current_index then
+    logger.log('current problem not found in contest', vim.log.levels.ERROR)
+    return
+  end
+
+  local new_index = current_index + delta
+
+  if new_index < 1 or new_index > #problems then
+    local msg = delta > 0 and 'at last problem' or 'at first problem'
+    logger.log(msg, vim.log.levels.WARN)
+    return
+  end
+
+  local new_problem = problems[new_index]
+  local setup = require('cp.setup')
+  setup.setup_problem(state.get_contest_id(), new_problem.id, language)
+end
+
+M.get_current_problem = get_current_problem
+
+return M