#!/usr/bin/python
import sys, os, subprocess
import options
from helpers import *

optspec = """
redo [targets...]
--
d,debug    print dependency checks as they happen
v,verbose  print commands as they are run
ifchange   only redo if the file is modified or deleted
ifcreate   only redo if the file is created
"""
o = options.Options('redo', optspec)
(opt, flags, extra) = o.parse(sys.argv[1:])

targets = extra or ['it']


def log(s):
    sys.stdout.flush()
    sys.stderr.write('redo: %s%s' % (REDO_DEPTH, s))
    sys.stderr.flush()


def debug(s):
    if REDO_DEBUG:
        log(s)


def add_dep(t, mode, dep):
    open('.redo/dep.%s' % t, 'a').write('%s %s\n' % (mode, dep))
    

def find_do_file(t):
    dofile = '%s.do' % t
    if os.path.exists(dofile):
        add_dep(t, 'm', dofile)
        if dirty_deps(dofile, depth = ''):
            build(dofile)
        return dofile
    else:
        add_dep(t, 'c', dofile)
        return None


def _dirty_deps(t, depth):
    debug('%s?%s\n' % (depth, t))
    if not os.path.exists('.redo/stamp.%s' % t):
        debug('%s-- DIRTY (no stamp)\n' % depth)
        return True

    stamptime = os.stat('.redo/stamp.%s' % t).st_mtime
    try:
        realtime = os.stat(t).st_mtime
    except OSError:
        realtime = 0

    if stamptime != realtime:
        debug('%s-- DIRTY (mtime)\n' % depth)
        return True
    
    for sub in open('.redo/dep.%s' % t).readlines():
        assert(sub[0] in ('c','m'))
        assert(sub[1] == ' ')
        assert(sub[-1] == '\n')
        mode = sub[0]
        name = sub[2:-1]
        if mode == 'c':
            if os.path.exists(name):
                debug('%s-- DIRTY (created)\n' % depth)
                return True
        elif mode == 'm':
            if dirty_deps(name, depth + '  '):
                #debug('%s-- DIRTY (sub)\n' % depth)
                return True
    return False


def dirty_deps(t, depth):
    if _dirty_deps(t, depth):
        unlink('.redo/stamp.%s' % t)  # short circuit future checks
        return True
    return False


def stamp(t):
    stampfile = '.redo/stamp.%s' % t
    open(stampfile, 'w').close()
    try:
        mtime = os.stat(t).st_mtime
    except OSError:
        mtime = 0
    os.utime(stampfile, (mtime, mtime))


def build(t):
    unlink('.redo/dep.%s' % t)
    open('.redo/dep.%s' % t, 'w').close()
    dofile = find_do_file(t)
    if not dofile:
        if os.path.exists(t):  # an existing source file
            stamp(t)
            return  # success
        else:
            raise Exception('no rule to make %r' % t)
    unlink(t)
    os.putenv('REDO_TARGET', t)
    os.putenv('REDO_DEPTH', REDO_DEPTH + '  ')
    tmpname = '%s.redo.tmp' % t
    unlink(tmpname)
    f = open(tmpname, 'w+')
    argv = ['sh', '-e', dofile, t, 'FIXME', tmpname]
    if REDO_VERBOSE:
        argv[1] += 'v'
    log('%s\n' % t)
    rv = subprocess.call(argv, stdout=f.fileno())
    st = os.stat(tmpname)
    #log('rv: %d (%d bytes) (%r)\n' % (rv, st.st_size, dofile))
    stampfile = '.redo/stamp.%s' % t
    if rv==0:
        if st.st_size:
            os.rename(tmpname, t)
        else:
            unlink(tmpname)
        stamp(t)
    else:
        unlink(tmpname)
        unlink(stampfile)
    f.close()
    if rv != 0:
        raise Exception('non-zero return code building %r' % t)


assert(not (opt.ifchange and opt.ifcreate))

mkdirp('.redo')
REDO_TARGET = os.getenv('REDO_TARGET', '')
REDO_DEPTH = os.getenv('REDO_DEPTH', '')

if not REDO_DEPTH:
    exenames = [os.path.abspath(sys.argv[0]), os.path.realpath(sys.argv[0])]
    if exenames[0] == exenames[1]:
        exenames = [exenames[0]]
    dirnames = [os.path.dirname(p) for p in exenames]
    os.putenv('PATH', ':'.join(dirnames) + ':' + os.getenv('PATH'))

if opt.debug:
    REDO_DEBUG = 1
    os.putenv('REDO_DEBUG', '1')
else:
    REDO_DEBUG = os.getenv('REDO_DEBUG', '') and 1 or 0
if opt.verbose:
    REDO_VERBOSE = 1
    os.putenv('REDO_VERBOSE', '1')
else:
    REDO_VERBOSE = os.getenv('REDO_VERBOSE', '') and 1 or 0

for t in targets:
    if REDO_TARGET:
        add_dep(REDO_TARGET, opt.ifcreate and 'c' or 'm', t)
    if opt.ifcreate:
        pass # just adding the dependency (above) is enough
    elif opt.ifchange:
        if dirty_deps(t, depth = ''):
            build(t)
    else:
        build(t)