from __future__ import annotations
from typing import TYPE_CHECKING

from pydantic import BaseModel
from typing import Any, List
from pulp import LpProblem, LpVariable, lpSum

import logging

from models.solution import Solution
from models.item import Item
from models.bundle import Bundle

from lib.errors.item_generation_error import ItemGenerationError

if TYPE_CHECKING:
    from models.solver_run import SolverRun

class Problem(BaseModel):
    items: List[Item]
    bundles: List[Bundle]
    problem: Any
    solver_items_var: Any = None
    solver_bundles_var: Any = None

    def __init__(self, **data) -> None:
        super().__init__(**data)

        # setup common Solver variables
        self.solver_items_var = LpVariable.dicts("Item",
                                    [item.id for item in self.items],
                                    lowBound=0,
                                    upBound=1,
                                    cat='Binary')
        self.solver_bundles_var = LpVariable.dicts("Bundle",
                                    [bundle.id for bundle in self.bundles],
                                    lowBound=0,
                                    upBound=1,
                                    cat='Binary')

    def solve(self) -> LpProblem:
        self.problem.solve()
        return self.problem

    def generate(self, solution: Solution, solver_run: SolverRun) -> None:
        try:
            # creating problem objective function
            solver_run.objective_function.for_problem(self)

            logging.info('Creating Constraints...')
            # generic constraints
            for constraint in solver_run.constraints:
                constraint.build(self, solver_run=solver_run, solution=solution)

            # irt target constraints
            for target in solver_run.objective_function.all_targets():
                target.constraints(self, solver_run)

            logging.info('Constraints Created...')
        except ValueError as error:
            logging.error(error)
            raise ItemGenerationError(
                error.msg,
                error.args[0])