use std::collections::BTreeSet;

use crate::prelude::*;

fn do_merge(
    txn1_ref: &data::TransactionRef,
    txn2_ref: &data::TransactionRef,
    common: data::AccountName,
) {
    let mut txn1 = txn1_ref.borrow_mut();
    let mut txn2 = txn2_ref.borrow_mut();

    show::show_transaction(None, &txn1);
    show::show_transaction(None, &txn2);

    assert_eq!(txn1.changes.len(), 2);
    assert_eq!(txn2.changes.len(), 2);

    let (change1, mut rest1) = txn1.split_changes_mut(common).unwrap();
    let (change2, mut rest2) = txn2.split_changes_mut(common).unwrap();

    let other1 = rest1.next().unwrap();
    let other2 = rest2.next().unwrap();

    drop(rest1);
    drop(rest2);

    change1.account = other2.account;
    change2.account = other1.account;

    // ghost whichever is the deposit
    if change1.amount.is_sign_positive() {
        txn1.annotations
            .insert("ghost".to_string(), txn2.id().unwrap().to_string());
    } else {
        txn2.annotations
            .insert("ghost".to_string(), txn1.id().unwrap().to_string());
    }
}

#[derive(cliask::ActionEnum)]
enum Action {
    Skip,
    Merge,
    Ignore,
    Finish,
    Abort,
}

pub fn do_match(data: &mut data::Hoard, account: data::AccountName) -> anyhow::Result<bool> {
    let Some(account_data) = data.ledger_data_for(account) else {
        log::warn!("No data for account {account}");
        return Ok(false);
    };

    let mut killed = vec![];
    let mut skip = BTreeSet::<data::TransactionRef>::new();

    let mut sorted_data: Vec<_> = account_data.into();
    sorted_data.sort_by_key(|d| d.borrow().datestamp);

    let search_window = chrono::Days::new(7);

    'outer_loop: for txn_ref in &sorted_data {
        if skip.contains(txn_ref) {
            continue;
        }
        let txn = txn_ref.borrow();
        if txn.id().is_none() {
            continue;
        }

        let (_, mut txn_known_it) = txn.split_changes(account).unwrap();
        let txn_known = txn_known_it.next().unwrap();
        drop(txn_known_it);

        let amount = *txn.change_for(account).unwrap().amount;

        // go one week prior and after
        let range_start = sorted_data
            .binary_search_by_key(
                &txn.datestamp.checked_sub_days(search_window).unwrap(),
                |d| d.borrow().datestamp,
            )
            .unwrap_or_else(|a| a);
        let range_end = sorted_data
            .binary_search_by_key(
                &txn.datestamp.checked_add_days(search_window).unwrap(),
                |d| d.borrow().datestamp,
            )
            .unwrap_or_else(|a| a);

        for otxn_ref in sorted_data.iter().take(range_end).skip(range_start) {
            if skip.contains(otxn_ref) {
                continue;
            }
            let otxn = otxn_ref.borrow();

            if otxn.id().is_none() {
                continue;
            }

            let (_, mut otxn_known_it) = otxn.split_changes(account).unwrap();
            let otxn_known = otxn_known_it.next().unwrap();
            drop(otxn_known_it);

            if otxn_known.account == txn_known.account {
                continue;
            }

            if *otxn.change_for(account).unwrap().amount == -amount {
                println!("==== Candidate match ====");

                show::show_transaction(Some(data), &txn);
                println!();
                show::show_transaction(Some(data), &otxn);

                match cliask::ActionPrompt::new()
                    .with_default(Action::Skip)
                    .run()?
                {
                    Action::Finish => break 'outer_loop,
                    Action::Skip => continue,
                    Action::Ignore => break,
                    Action::Merge => {
                        drop(txn);
                        drop(otxn);
                        killed.push(do_merge(txn_ref, otxn_ref, account));
                        skip.insert(txn_ref.clone());
                        skip.insert(otxn_ref.clone());
                        break;
                    }
                    Action::Abort => return Ok(false),
                }
            }
        }
    }

    Ok(!skip.is_empty())
}