RailRoad Implementation

[blurbeast]

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📌 Issue: Complete Implementation of RailRoadTrait for Railroad Model

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🧩 Description

The RailRoadTrait defines key functionalities for managing railroad properties in the game. While the structure is in place, the methods are currently incomplete or incorrectly defined ( missing logic).

This issue tracks the implementation and correction of all trait functions.

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✅ Acceptance Criteria

• change_railroad_ownership() should:

  • Use ref self to mutate the owner field.
  • Validate that the caller is the current owner.
  • Only allow ownership change if for_sale is true and is_mortgaged is false.

• get_rent_amount() should:

  • Be a pure/read-only method (no mut).
  • Return correct rent based on how many railroads are owned (1 to 4).
  • Return 0 if the railroad is mortgaged.

• mortgage() and lift_mortgage() should:

  • Use ref self to mutate is_mortgaged.
  • Ensure caller is the current owner before modifying.

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🛠️ Example Fixes

fn change_railroad_ownership(ref self: RailRoad, new_owner: ContractAddress, owner: ContractAddress) -> bool {
    if self.owner != owner || self.is_mortgaged || !self.for_sale {
        return false;
    }
    self.owner = new_owner;
    self.for_sale = false;
    true
}

fn get_rent_amount(railroad: RailRoad, railroad_owned: u8) -> u256 {
    if railroad.is_mortgaged {
        return 0;
    }
    match railroad_owned {
        1 => 25,
        2 => 50,
        3 => 100,
        4 => 200,
        _ => 0,
    }
}

fn mortgage(ref self: RailRoad, owner: ContractAddress) {
    if self.owner == owner {
        self.is_mortgaged = true;
    }
}

fn lift_mortgage(ref self: RailRoad, owner: ContractAddress) {
    if self.owner == owner {
        self.is_mortgaged = false;
    }
}

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📘 Status

Build: ✅ Should build successfully
Validation: 🚧 Pending full logic implementation

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