-- SCL Parser utilities for the LSP server
local M = {}

function M.extract_variables(content)
  local variables = {}
  local variable_positions = {}

  local lines = {}
  for line in content:gmatch("([^\n]*)\n") do
    table.insert(lines, line)
  end

  local in_var_section = false
  local in_struct_section = false
  local var_type = "unknown"
  local current_block = nil

  local function process_line(line, line_num)
    local trimmed = line:gsub("^%s+", ""):gsub("%s+$", "")

    -- Detect block start (with or without quotes)
    local fb_name = trimmed:match('FUNCTION_BLOCK%s+"([^"]+)"') or trimmed:match("^FUNCTION_BLOCK%s+([%w_]+)")
    if fb_name then
      current_block = { name = fb_name, kind = "function_block" }
      in_var_section = false
      in_struct_section = false
      return
    end

    local ob_name = trimmed:match('ORGANIZATION_BLOCK%s+"([^"]+)"') or trimmed:match("^ORGANIZATION_BLOCK%s+([%w_]+)")
    if ob_name then
      current_block = { name = ob_name, kind = "organization_block" }
      in_var_section = false
      in_struct_section = false
      return
    end

    local fn_name = trimmed:match('FUNCTION%s+"([^"]+)"') or trimmed:match("^FUNCTION%s+([%w_]+)")
    if fn_name then
      current_block = { name = fn_name, kind = "function" }
      in_var_section = false
      in_struct_section = false
      return
    end

    if trimmed:match("^END_FUNCTION_BLOCK") or
       trimmed:match("^END_ORGANIZATION_BLOCK") or
       trimmed:match("^END_FUNCTION") then
      current_block = nil
      in_var_section = false
      in_struct_section = false
      return
    end

    -- Handle TYPE sections (for .udt files with STRUCT)
    if trimmed:match("^TYPE") and (trimmed:match("^TYPE%s") or trimmed:match('^TYPE"') or trimmed == "TYPE") then
      in_struct_section = true
      var_type = "STRUCT_FIELD"
      return
    end

    if trimmed:match("^END_TYPE") then
      in_struct_section = false
      return
    end

    if trimmed:match("^VAR[_A-Z]*%s*$") or
       trimmed:match("^VAR_INPUT%s*$") or
       trimmed:match("^VAR_OUTPUT%s*$") or
       trimmed:match("^VAR_IN_OUT%s*$") or
       trimmed:match("^VAR_TEMP%s*$") or
       trimmed:match("^VAR[_ ]*CONSTANT%s*$") or
       trimmed:match("^VAR[_ ]*RETAIN%s*$") or
       trimmed:match("^VAR[_ ]*NON_RETAIN%s*$") then
      in_var_section = true
      in_struct_section = false
      if trimmed:match("INPUT") then var_type = "VAR_INPUT"
      elseif trimmed:match("OUTPUT") then var_type = "VAR_OUTPUT"
      elseif trimmed:match("IN_OUT") then var_type = "VAR_IN_OUT"
      elseif trimmed:match("TEMP") then var_type = "VAR_TEMP"
      elseif trimmed:match("CONSTANT") then var_type = "VAR_CONSTANT"
      elseif trimmed:match("RETAIN") then var_type = "VAR_RETAIN"
      elseif trimmed:match("NON_RETAIN") then var_type = "VAR_NON_RETAIN"
      else var_type = "VAR" end
      return
    end

    if trimmed:match("^END_VAR%s*$") then
      in_var_section = false
      return
    end

    if trimmed:match("^STRUCT%s*$") then
      in_struct_section = true
      var_type = "STRUCT_FIELD"
      return
    end

    if trimmed:match("^END_STRUCT%s*$") then
      in_struct_section = false
      return
    end

    if not in_var_section and not in_struct_section then return end

    if trimmed:match("^%(%*") or trimmed:match("^%s*//") then
      return
    end

    local var_name = trimmed:match("^([%w_]+)%s*%b{}%s*:") or trimmed:match("^([%w_]+)%s*:")
    if not var_name then
      var_name = trimmed:match("^([%w_]+)%s*%b{}%s*,") or trimmed:match("^([%w_]+)%s*,")
    end

    if var_name and not variables[var_name] then
      local col = line:find(var_name, 1, true)
      if col then
        local type_start = nil
        local brace_depth = 0
        for i = 1, #line do
          local c = line:sub(i, i)
          if c == "{" then
            brace_depth = brace_depth + 1
          elseif c == "}" then
            brace_depth = brace_depth - 1
          elseif c == ":" and brace_depth == 0 then
            type_start = i
            break
          end
        end
        local var_data_type = "unknown"
        local var_comment = line:match("//%s*(.+)$")
        if not var_comment then
          var_comment = line:match("%(%*(.-)%*%)")
        end
        if type_start then
          local type_part = line:sub(type_start + 1)
          type_part = type_part:gsub("%s*:=.*$", "")
          type_part = type_part:gsub("%s*;.*$", "")
          type_part = type_part:gsub("^%s+", "")
          type_part = type_part:gsub("%s+$", "")
          var_data_type = type_part
        end

        variables[var_name] = {
          type = var_type,
          data_type = var_data_type,
          line = line_num,
          character = col - 1,
          comment = var_comment,
        }
        variable_positions[var_name] = {
          line = line_num,
          character = col - 1,
        }
      end
    end
  end

  for i, line in ipairs(lines) do
    process_line(line, i - 1)
  end

  return variables, variable_positions
end

function M.extract_types(content)
  local types = {}

  local lines = {}
  for line in content:gmatch("([^\n]*)\n") do
    table.insert(lines, line)
  end

  local in_type_section = false
  local current_type = nil
  local brace_depth = 0
  local in_struct = false
  local pending_type_name = nil
  local pending_comment = nil

  local function extract_type_name(after_colon)
    if not after_colon then return nil end
    local quoted = after_colon:match('^%s*"([^"]+)"')
    if quoted then return quoted end
    return after_colon:match("^%s*(%w+)")
  end

  for i, line in ipairs(lines) do
    local trimmed = line:gsub("^%s+", ""):gsub("%s+$", "")

    local is_comment_only = trimmed:match("^//")
    if is_comment_only then
      pending_comment = line:match("//%s*(.+)$")
    end

    local is_type_line = trimmed:match("^TYPE") and (trimmed:match("^TYPE%s") or trimmed:match('^TYPE"') or trimmed == "TYPE")
    
    if is_type_line then
      in_type_section = true
      in_struct = false
      brace_depth = 0
      pending_type_name = trimmed:match('^TYPE%s+"([^"]+)') or trimmed:match("^TYPE%s+(%w+)")
      if not pending_comment then
        pending_comment = trimmed:match("//%s*(.+)$")
      end
    elseif in_type_section and trimmed:match("^END_TYPE") then
      in_type_section = false
      in_struct = false
      current_type = nil
      pending_type_name = nil
    elseif in_type_section then
      local type_name_with_struct = trimmed:match("^(%w+)%s+.-:%s+STRUCT")
      if type_name_with_struct then
        current_type = {
          name = type_name_with_struct,
          kind = "struct",
          fields = {},
          start_line = i - 1,
          comment = pending_comment,
        }
        types[type_name_with_struct] = current_type
        in_struct = true
        pending_type_name = nil
        pending_comment = nil
      elseif trimmed:match("^STRUCT%s*$") then
        if pending_type_name then
          current_type = {
            name = pending_type_name,
            kind = "struct",
            fields = {},
            start_line = i - 1,
            comment = pending_comment,
          }
          types[pending_type_name] = current_type
          pending_type_name = nil
          pending_comment = nil
        end
        in_struct = true
      elseif trimmed:match("^END_STRUCT%s*$") then
        in_struct = false
      elseif in_struct and current_type and current_type.fields then
        local field_name = line:match("^%s*(%w+)%s*:%s*")
        if field_name then
          local after_colon = line:match(":%s*(.+)")
          local field_type = after_colon and extract_type_name(after_colon)
          local field_comment = line:match("//%s*(.+)$")
          if not field_comment then
            field_comment = line:match("%(%*(.-)%*%)")
          end
          table.insert(current_type.fields, {
            name = field_name,
            type = field_type or "unknown",
            comment = field_comment,
          })
        end
      elseif not in_struct and not pending_type_name then
        local array_match = trimmed:match("^(%w+)%s+:%s+ARRAY")
        if array_match then
          local of_type = trimmed:match("OF%s+(%w+)")
          current_type = {
            name = array_match,
            kind = "array",
            element_type = of_type,
            start_line = i - 1,
          }
          types[array_match] = current_type
        else
          local alias_match = trimmed:match("^(%w+)%s+:%s+(%w+)")
          if alias_match then
            local base_type = extract_type_name(trimmed:match(":%s+(.+)$"))
            current_type = {
              name = alias_match,
              kind = "alias",
              base_type = base_type,
              start_line = i - 1,
            }
            types[alias_match] = current_type
          end
        end
      end
    end
  end

  return types
end

function M.extract_functions(content)
  local functions = {}

  local lines = {}
  for line in content:gmatch("([^\n]*)\n") do
    table.insert(lines, line)
  end

  local function find_block_end(start_line, block_name, end_markers)
    local depth = 1
    for i = start_line + 1, #lines do
      local line = lines[i]
      if line:match("^%s*" .. block_name) then
        depth = depth + 1
      end
      for _, marker in ipairs(end_markers) do
        if line:match("^%s*" .. marker) then
          depth = depth - 1
          if depth == 0 then return i end
        end
      end
    end
    return #lines
  end

  for i, line in ipairs(lines) do
    local func_name = line:match('FUNCTION%s+"([^"]+)"') or line:match("^FUNCTION%s+([%w_]+)")
    if func_name then
      local end_line = find_block_end(i, "END_FUNCTION", { "END_FUNCTION" })
      table.insert(functions, {
        name = func_name,
        kind = "function",
        start = i - 1,
        final = end_line - 1,
      })
    end

    local fb_name = line:match('FUNCTION_BLOCK%s+"([^"]+)"') or line:match("^FUNCTION_BLOCK%s+([%w_]+)")
    if fb_name then
      local end_line = find_block_end(i, "END_FUNCTION_BLOCK", { "END_FUNCTION_BLOCK" })
      table.insert(functions, {
        name = fb_name,
        kind = "function_block",
        start = i - 1,
        final = end_line - 1,
      })
    end

    local ob_name = line:match('ORGANIZATION_BLOCK%s+"([^"]+)"') or line:match("^ORGANIZATION_BLOCK%s+([%w_]+)")
    if ob_name then
      local end_line = find_block_end(i, "END_ORGANIZATION_BLOCK", { "END_ORGANIZATION_BLOCK" })
      table.insert(functions, {
        name = ob_name,
        kind = "organization_block",
        start = i - 1,
        final = end_line - 1,
      })
    end
  end

  return functions
end

return M