#!/usr/bin/env python

import json, sys, os, hashlib

if len(sys.argv) < 2:
    print "You must specify the pipeline configuration as argument."
    sys.exit(1)

rules = []
commands = []

def parse_dependencies(j):
    return [v for k , v, in j.items()]

def eq(js, config_name):
    f = open(config_name)
    cd = f.read()
    f.close()
    js5 = hashlib.md5()
    js5.update(js)
    cn5 = hashlib.md5()
    cn5.update(cd)
    return js5.digest() == cn5.digest()

def write_config(target, config, variables):
    config_name = ".pipeline/config.json." + target.replace("/", "_") + ".cfg"
    if "target" in config:
        print "found reserved word 'target' in configuration of " + target
        sys.exit(1)
    # add 'target' to the config so that the executed command can
    # access it
    config["target"] = target
    # remove comments so that a change in the command does not result in
    # the execution of the stage
    config.pop("comment", "")

    # update the configuration only if it does not exist or
    # the content has changed
    # this will trigger a new execution of the stage
    js = replace_vars(json.dumps(config), variables)

    if not os.path.exists(config_name) or not eq(js, config_name):
        print "writing configuration " + config_name + " ..."
        open(config_name, "w").write(js)

    return config_name

def replace_vars(s, variables):
    r = s
    for key, val in variables.items():
        r = r.replace("$$" + key + "$$", str(val))
    return r


if not os.path.exists(".pipeline"):
    os.makedirs(".pipeline")

j = json.loads(open(sys.argv[1]).read())

variables = j.get("variables", {})

for target, v in j["stages"].items():
    config_name = write_config(target, v, variables)
    rules.append(
        target + ": " + 
        " ".join([replace_vars(b, variables) for a, b in v["dependencies"].items()]) + " " + config_name
    )
    cpth = os.getcwdu() + "/" + config_name
    cmd = replace_vars(v["command"], variables)
    commands.append(
        "@echo '\x1b[33;01m'executing target\x1b[0m [\"" + target + "\"], " +
        "'\x1b[33;01m'cmd\x1b[0m [\"" + cmd + "\"]\n\t" +
        "@PIPELINE_CONFIG=" + cpth + " sh -c '" + cmd + "'"
    )

# generate Makefile
print "writing Makefile ..."
f = open("Makefile", "w")
print >> f, "all: Makefile " + " ".join(j["targets"])
print >> f
print >> f, "Makefile: " + sys.argv[1]
print >> f, "\t" + sys.argv[0] + " " + sys.argv[1]
for i, j in zip(rules, commands):
    print >> f
    print >> f, i
    print >> f, "\t" + j
print >> f, "\nclean:"
print >> f, "\trm -rf .pipeline"