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use clockwork_utils::{InstructionData, AccountMetaData, anchor_sighash};

use {crate::objects::*, anchor_lang::prelude::*, clockwork_utils::CrankResponse};

#[derive(Accounts)]
pub struct SnapshotEntryDelete<'info> {
    #[account(address = Config::pubkey())]
    pub config: Account<'info, Config>,

    #[account(
        mut, 
        address = config.epoch_queue
    )]
    pub queue: Signer<'info>,

    #[account(
        address = Registry::pubkey(),
        constraint = !registry.locked
    )]
    pub registry: Account<'info, Registry>,

    #[account(
        mut,
        seeds = [
            SEED_SNAPSHOT,
            snapshot.id.to_be_bytes().as_ref(),
        ],
        bump,
        constraint = snapshot.id.lt(&registry.current_epoch)
    )]
    pub snapshot: Account<'info, Snapshot>,

    #[account(
        mut,
        seeds = [
            SEED_SNAPSHOT_ENTRY,
            snapshot_entry.snapshot_frame.as_ref(),
            snapshot_entry.id.to_be_bytes().as_ref(),
        ],
        bump,
        has_one = snapshot_frame
    )]
    pub snapshot_entry: Account<'info, SnapshotEntry>,

    #[account(
        mut,
        seeds = [
            SEED_SNAPSHOT_FRAME,
            snapshot_frame.snapshot.as_ref(),
            snapshot_frame.id.to_be_bytes().as_ref(),
        ],
        bump,
        has_one = snapshot,
    )]
    pub snapshot_frame: Account<'info, SnapshotFrame>,
}

pub fn handler(ctx: Context<SnapshotEntryDelete>) -> Result<CrankResponse> {
    // Get accounts
    let config = &ctx.accounts.config;
    let queue = &mut ctx.accounts.queue;
    let registry = &ctx.accounts.registry;
    let snapshot = &mut ctx.accounts.snapshot;
    let snapshot_entry = &mut ctx.accounts.snapshot_entry;
    let snapshot_frame = &mut ctx.accounts.snapshot_frame;

    // Close the snapshot entry account.
    let snapshot_entry_lamports = snapshot_entry.to_account_info().lamports();
    **snapshot_entry.to_account_info().lamports.borrow_mut() = 0;
    **queue.to_account_info().lamports.borrow_mut() = queue
        .to_account_info()
        .lamports()
        .checked_add(snapshot_entry_lamports)
        .unwrap();

    // If this frame has no more entries, then close the frame account.
    if snapshot_entry.id.checked_add(1).unwrap().eq(&snapshot_frame.total_entries) {
        let snapshot_frame_lamports = snapshot_frame.to_account_info().lamports();
        **snapshot_frame.to_account_info().lamports.borrow_mut() = 0;
        **queue.to_account_info().lamports.borrow_mut() = queue
            .to_account_info()
            .lamports()
            .checked_add(snapshot_frame_lamports)
            .unwrap();


        // If this is also the last frame in the snapshot, then close the snapshot account.
        if snapshot_frame.id.checked_add(1).unwrap().eq(&snapshot.total_frames) {
            let snapshot_lamports = snapshot.to_account_info().lamports();
            **snapshot.to_account_info().lamports.borrow_mut() = 0;
            **queue.to_account_info().lamports.borrow_mut() = queue
                .to_account_info()
                .lamports()
                .checked_add(snapshot_lamports)
                .unwrap();
        }
    }

    // Build the next instruction
    let next_instruction = if snapshot_entry.id.checked_add(1).unwrap().lt(&snapshot_frame.total_entries) {
        // Move on to the next entry.
        Some(InstructionData {
            program_id: crate::ID,
            accounts: vec![
                AccountMetaData::new_readonly(config.key(), false),
                AccountMetaData::new(queue.key(), true),
                AccountMetaData::new_readonly(registry.key(), false),
                AccountMetaData::new(snapshot.key(), false),
                AccountMetaData::new(SnapshotEntry::pubkey(snapshot_frame.key(), snapshot_entry.id.checked_add(1).unwrap()), false),
                AccountMetaData::new(snapshot_frame.key(), false),
            ],
            data: anchor_sighash("snapshot_entry_delete").to_vec(),
        })
    } else if snapshot_frame.id.checked_add(1).unwrap().lt(&snapshot.total_frames) {
        // This frame has no more entries. Move onto the next frame.
        Some(InstructionData {
            program_id: crate::ID,
            accounts: vec![
                AccountMetaData::new_readonly(config.key(), false),
                AccountMetaData::new(queue.key(), true),
                AccountMetaData::new_readonly(registry.key(), false),
                AccountMetaData::new(snapshot.key(), false),
                AccountMetaData::new(SnapshotFrame::pubkey(snapshot.key(), snapshot_frame.id.checked_add(1).unwrap()), false),
            ],
            data: anchor_sighash("snapshot_frame_delete").to_vec(),
        })
    } else {
        // This frame as no more entires and it was the last frame in the snapshot. We are done!
        None
    };

    Ok( CrankResponse { next_instruction, ..CrankResponse::default() } )
}