#This script is designed to run with Understand - CodeCheck
use base ("Understand::Codecheck");
use strict;
use warnings;


# Required - Return the short name of the check
sub name { return "Unnecessary Imports";}

# Required - Return the short description of the check
sub description { return "Identify Imports that are unnecessary";}

# Required - Return the long description of the check
sub detailed_description { return "Identify Imports that are unnecessary";}

# Required - Test the language of the current file, the check will be 
# skipped if this returns 0
sub test_language {
  my $language = shift;
  return $language eq "Python" 
}

# Required - Return 1 if this check will be run on a per-entity basis
# Currently only supported on a per-file basis
sub test_entity { return 1;}

# Required - Return 1 if this check should be run on the entire project
# regardless of what files are selected. Should only be used for 
# project-level checks
sub test_global { return 0;}

# Optional - define configurable options for the check.
sub define_options{
  my $check = shift;  
}


# Required - Run the check and return violations if any.
# This is called for each file if test_entity is set to 1 and $file is the Understand::Ent object for the file
# it is also called once with $file set to null if test_global is set to 1
sub check {
  my $check = shift; #The check object, needed to report violations and lookup option values
  my $file = shift;  # Will be empty if test_global set to 1 and test_entity set to 0
  
  # test_entity only runs on files for now, but could change in the future, so force the check to only run on files
  return unless $file->kind->check("file"); 
  my @includes = $file->refs("import","",1);
  return unless @includes;

  my $depends = $file->depends();
  return unless $depends;
  INC:foreach my $incRef (@includes){
    $check->violation($incRef->ent,$file,-1,-1,@includes." imports");
    my $modDef = $incRef->ent->ref("define");
    if (! $modDef){
      $check->violation($incRef->ent,$file,$incRef->line,$incRef->column,"import module not found");
      next INC;
    }
    my $modFile = $modDef->file;
    my @fileDeps = $depends->value($modFile);
    DEP:foreach my $depRef (@fileDeps){
      next DEP if $depRef->kind->check("import");
      next INC;
    }
    $check->violation($incRef->ent,$file,$incRef->line,$incRef->column,"import file not directly used"); 
  }
}