# Title: Project 2 - Parse a bushfire scenario file
# Author: Rory Healy
# Date created - 8th May 2019
# Date modified - 9th May 2019

def strlist_to_listlist(grid):
    '''Converts a list of strings into a list of lists.'''
    for i in range(len(grid)):
        line_to_append = []
        for j in range(len(grid[i])):
            current_coordinate = grid[i][j]
            if current_coordinate not in ",":
                line_to_append.append(int(grid[i][j]))
        grid[i] = line_to_append
    return grid


def parse_scenario(filename):
    '''Parses a file with the structure described, validates the contents and
    returns a dictionary containing all values that are required to model a
    scenario, or None if any of the contents are invalid.'''
    
    structure_dict = {}
    
    # Converts the file to a list of strings.
    structure = open(filename, "r")
    all_lines = []
    for line in structure.readlines():
        line = line[:-1]
        all_lines.append(line)
    
    # Finds the length of the matrix and splits the data up acccordingly.
    # e.g. a M*M matrix will store f_grid and h_grid as a list of M lists.
    # This is used to return the f_grid and h_grid in the correct format.
    matrix_size = int(all_lines[0])
    if matrix_size <= 0:
        return None
    f_grid = []
    h_grid = []
    for i in range(1, matrix_size + 1):
        f_grid.append(all_lines[i])
    for i in range(matrix_size + 1, matrix_size * 2 + 1):
        h_grid.append(all_lines[i])
    strlist_to_listlist(f_grid)
    strlist_to_listlist(h_grid)
    
    # Remove matrix_size, f_grid and h_grid from all_lines and define
    # i_threshold, w_direction and burn_seeds so that they can be added to
    # structure_dict.
    all_lines = all_lines[((matrix_size * 2) + 1):]
    i_threshold = int(all_lines[0])
    w_direction = '' + all_lines[1]
    if all_lines[2]:
        burn_seeds = []
        burn_seeds.append(all_lines[2])
        burn_seeds = [(int(burn_seeds[0][0]), int(burn_seeds[0][-1]))]

    # Checks if the values are valid.
    if i_threshold > 8 or i_threshold < 0:
        return None
    for i in range(len(burn_seeds)):
        current_seeds = list(burn_seeds[i])
        for j in range(len(current_seeds)):
            if current_seeds[j] > matrix_size:
                return None
    
    # Fills in structure_dict with the keys and associated values.
    all_dict_keys = ['f_grid', 'h_grid', 'i_threshold', 'w_direction', 
                     'burn_seeds']
    all_dict_values = [f_grid, h_grid, i_threshold, w_direction, burn_seeds]
    for i in range(len(all_dict_values)):
        structure_dict[all_dict_keys[i]] = all_dict_values[i]

    structure.close()
    return structure_dict