use crate::budget_expr::BudgetExpr;
use crate::id;
use chrono::prelude::{DateTime, Utc};
use serde_derive::{Deserialize, Serialize};
use solana_sdk::pubkey::Pubkey;
use solana_sdk::transaction_builder::BuilderInstruction;

/// A smart contract.
#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub struct Contract {
    /// The number of lamports allocated to the `BudgetExpr` and any transaction fees.
    pub lamports: u64,
    pub budget_expr: BudgetExpr,
}

/// An instruction to progress the smart contract.
#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
pub enum BudgetInstruction {
    /// Declare and instantiate `BudgetExpr`.
    InitializeAccount(BudgetExpr),

    /// Tell a payment plan acknowledge the given `DateTime` has past.
    ApplyTimestamp(DateTime<Utc>),

    /// Tell the budget that the `InitializeAccount` with `Signature` has been
    /// signed by the containing transaction's `Pubkey`.
    ApplySignature,
}

impl BudgetInstruction {
    pub fn new_initialize_account(contract: &Pubkey, expr: BudgetExpr) -> BuilderInstruction {
        let mut keys = vec![];
        if let BudgetExpr::Pay(payment) = &expr {
            keys.push((payment.to, false));
        }
        keys.push((*contract, false));
        BuilderInstruction::new(id(), &BudgetInstruction::InitializeAccount(expr), keys)
    }

    pub fn new_apply_timestamp(
        from: &Pubkey,
        contract: &Pubkey,
        to: &Pubkey,
        dt: DateTime<Utc>,
    ) -> BuilderInstruction {
        let mut keys = vec![(*from, true), (*contract, false)];
        if from != to {
            keys.push((*to, false));
        }
        BuilderInstruction::new(id(), &BudgetInstruction::ApplyTimestamp(dt), keys)
    }

    pub fn new_apply_signature(
        from: &Pubkey,
        contract: &Pubkey,
        to: &Pubkey,
    ) -> BuilderInstruction {
        let mut keys = vec![(*from, true), (*contract, false)];
        if from != to {
            keys.push((*to, false));
        }
        BuilderInstruction::new(id(), &BudgetInstruction::ApplySignature, keys)
    }
}