use std::collections::BTreeMap;

use itertools::Itertools;

use crate::data::{Root, SourceFile, Span, Spanned};

use super::{LedgerEntry, Transaction};

fn print_transaction(root: &Root, tx: &Transaction, padding: usize) {
    println!(
        "{}: {}",
        tx.datestamp,
        tx.title.as_deref().unwrap_or("")
    );

    if !tx.annotations.is_empty() {
        println!(
            "    {}",
            tx.annotations.iter().map(|a| format!("[{a}]")).join(" ")
        );
    }

    let force_show = tx.changes.iter().unique_by(|b| *b.account).count() > 1;

    for change in &tx.changes {
        let spacer = if change.amount.is_sign_positive() {
            " "
        } else {
            ""
        };

        let balance = if let Some(bal) = change.balance {
            format!(" = {bal}")
        } else {
            String::new()
        };


        if Some(change.unit.as_ref()) == root.account_spec(*change.account).unwrap().unit.as_ref()
            && !force_show
        {
            println!(" - {:padding$}: {spacer}{}{balance}", change.account, change.amount,);
        } else {
            println!(
                " - {:padding$}: {spacer}{}{balance} {}",
                change.account, change.amount, change.unit,
            );
        }
    }
    // empty line afterwards
    println!();
}

fn print_comment(c: &Spanned<String>) {
    println!("{c}");
}

pub fn print_ledger<'l>(root: &Root, entries: impl Iterator<Item = &'l LedgerEntry>) {
    let mut ordering = BTreeMap::<SourceFile, BTreeMap<Span, &LedgerEntry>>::new();

    entries.for_each(|e| {
        ordering
            .entry(e.span().context)
            .or_default()
            .insert(e.span(), &e);
    });

    let Some(padding) = root.spec_root.accounts.keys().map(|k| k.len()).max() else {
        // no accounts
        return;
    };

    for (filename, entries) in ordering {
        println!(
            "==== file {} ====",
            std::path::Path::new(filename.as_ref()).display()
        );
        for (_span, le) in entries {
            match le {
                LedgerEntry::Transaction(tx) => print_transaction(root, tx, padding),
                LedgerEntry::Comment(c) => print_comment(c),
            }
        }
    }
}