"""Reporter foundation for Coverage."""

import os
from coverage.codeunit import code_unit_factory
from coverage.misc import CoverageException, NoSource

class Reporter(object):
    """A base class for all reporters."""
    
    def __init__(self, coverage, ignore_errors=False):
        """Create a reporter.
        
        `coverage` is the coverage instance. `ignore_errors` controls how
        skittish the reporter will be during file processing.

        """
        self.coverage = coverage
        self.ignore_errors = ignore_errors
        
        # The code units to report on.  Set by find_code_units.
        self.code_units = []
        
        # The directory into which to place the report, used by some derived
        # classes.
        self.directory = None

    def find_code_units(self, morfs, omit_prefixes):
        """Find the code units we'll report on.
        
        `morfs` is a list of modules or filenames. `omit_prefixes` is a list
        of prefixes to leave out of the list.
        
        """
        morfs = morfs or self.coverage.data.executed_files()
        self.code_units = code_unit_factory(
                            morfs, self.coverage.file_locator, omit_prefixes)
        self.code_units.sort()

    def report_files(self, report_fn, morfs, directory=None,
                        omit_prefixes=None):
        """Run a reporting function on a number of morfs.
        
        `report_fn` is called for each relative morf in `morfs`.
        
        """
        self.find_code_units(morfs, omit_prefixes)

        if not self.code_units:
            raise CoverageException("No data to report.")

        self.directory = directory
        if self.directory and not os.path.exists(self.directory):
            os.makedirs(self.directory)

        for cu in self.code_units:
            try:
                report_fn(cu, self.coverage._analyze(cu))
            except NoSource:
                if not self.ignore_errors:
                    raise
