from Parser import JobShopProblem as Problem
import random



def pull_fwd(solution):
""" Pull a task from a pseudo-random position to the position of 
    a random task forward. If the task directly in front is part 
    of the same job, pull that instead. The first task can never 
    be pulled forward. Will not rectify solutions.

    Returns the modified solution and the tasks index.
"""
    old_idx = random.randint(1, len(solution)-1)
    while(solution[old_idx][1][0] == solution[old_idx-1][1][0]):
        old_idx -= 1
    new_idx = random.randint(0, old_idx-1)
    for task in solution[new:old_idx]:
        if(task[1][0] == solution[old_idx][1][0]):
            break
    else:
        new_solution = solution[:]
        task = solution[old_idx]
        new_solution.remove(task)
        new_solution.insert(new_idx, task)
    return (new_solution, new_idx)


def accept(solution):
""" Accept the current generated solution and evaluate it.
    Maybe skip this during the first step to generate a more
    random solution.
"""
    return 3


def rectify(solution, idx):
""" Transform solution by adapting the begin times and delaying
    tasks on the same machine if affected.
"""
    global problem

    #move previous task on the same machine back if clash
""" task = solution[idx][1]
    prev_task = solution[idx-1][1]
    while(problem[task[0]][task[1]][1] == problem[prev_task[0]][prev_task[1]][1]):
        solution[idx-1][0] += problem[task[0]][task[1]][0] 
        solution[idx], solution[idx-1] = solution[idx-1], solution[idx]
        idx -= 1
        task = solution[idx][1]
        prev_task = solution[idx-1][1]
    del prev_task
""" 
    #make parallel
    solution[idx][0] = solution[idx-1][0]


def generate(solution, steps):
"""Generate a new solution from an existing solution with a 
    specified number of max steps.
"""
    options = [pull_fwd, accept]
    option = random.choice(options)
    return option(solution)


def mock():
""" Reads a mock problem and creates the corresponding enumerated 
    solution. Should clean up the namespace afterwards.
"""
    global problem
    global solution
    from Parser.js2_style import parse_file as mockload
    from SchedulingAlgorithms.enumerate import enumerate as mockenum
    problem = mockload('../inputdata/sample')
    solution = mockenum(problem)
    del mockload
    del mockenum