from pulp import lpSum, LpProblem
from random import randint, sample

import logging

from models.bundle import Bundle
from models.solver_run import SolverRun
from models.item import Item

from lib.errors.item_generation_error import ItemGenerationError

def build_constraints(solver_run: SolverRun, problem: LpProblem,
                      items: list[Item], bundles: list[Bundle]) -> LpProblem:
    logging.info('Creating Constraints...')

    try:
        total_form_items = solver_run.total_form_items
        constraints = solver_run.constraints

        for constraint in constraints:
            attribute = constraint.reference_attribute
            min = constraint.minimum
            max = constraint.maximum

            if attribute.type == 'metadata':
                logging.info('Metadata Constraint Generating...')
                con = dict(
                    zip([item.id for item in solver_run.items], [
                        item.attribute_exists(attribute)
                        for item in solver_run.items
                    ]))
                problem += lpSum([
                    con[item.id] * items[item.id] for item in solver_run.items
                ]) >= round(
                    total_form_items *
                    (min / 100)), f'{attribute.id} - {attribute.value} - min'
                problem += lpSum([
                    con[item.id] * items[item.id] for item in solver_run.items
                ]) <= round(
                    total_form_items *
                    (max / 100)), f'{attribute.id} - {attribute.value} - max'
            elif attribute.type == 'bundle':
                logging.info('Bundles Constraint Generating...')
                # TODO: account for many different bundle types, since the id condition in L33 could yield duplicates
                if solver_run.bundles != None:
                    # make sure the total bundles used in generated form is limited between min-max set
                    problem += lpSum([
                        bundles[bundle.id] for bundle in solver_run.bundles
                    ]) == randint(int(constraint.minimum),
                                  int(constraint.maximum))

        logging.info('Constraints Created...')
        return problem
    except ValueError as error:
        logging.error(error)
        raise ItemGenerationError(
            "Bundle min and/or max larger than bundle amount provided",
            error.args[0])


def get_random_bundles(total_form_items: int,
                       bundles: list[Bundle],
                       min: int,
                       max: int,
                       found_bundles=False) -> list[Bundle]:
    selected_bundles = None
    total_bundle_items = 0
    total_bundles = randint(min, max)
    logging.info(f'Selecting Bundles (total of {total_bundles})...')

    while found_bundles == False:
        selected_bundles = sample(bundles, total_bundles)
        total_bundle_items = sum(bundle.count for bundle in selected_bundles)

        if total_bundle_items <= total_form_items:
            found_bundles = True

    if found_bundles == True:
        return selected_bundles
    else:
        return get_random_bundles(total_form_items, total_bundles - 1, bundles)