use sanakirja_core::btree;
use sanakirja_core::btree::*;
use sanakirja_core::*;
use std::collections::HashSet;
use std::fs::File;
use std::io::{BufWriter, Write};
use std::path::Path;
pub fn debug<
    P: AsRef<Path>,
    T: LoadPage,
    K: Representable + ?Sized + std::fmt::Debug,
    V: Representable + ?Sized + std::fmt::Debug,
    PP: BTreePage<K, V>,
>(
    t: &T,
    db: &[&Db_<K, V, PP>],
    p: P,
    recurse: bool,
) where
    T::Error: std::fmt::Debug,
{
    let f = File::create(p.as_ref()).unwrap();
    let mut buf = BufWriter::new(f);
    writeln!(&mut buf, "digraph{{").unwrap();
    let mut h = HashSet::new();
    for db in db {
        print_page::<T, K, V, PP>(t, &mut h, &mut buf, &db.db.as_page(), recurse);
    }
    writeln!(&mut buf, "}}").unwrap();
}
fn print_page<
    T: LoadPage,
    K: Representable + ?Sized + std::fmt::Debug,
    V: Representable + ?Sized + std::fmt::Debug,
    P: btree::BTreePage<K, V>,
>(
    txn: &T,
    pages: &mut HashSet<u64>,
    buf: &mut BufWriter<File>,
    p: &Page,
    print_children: bool,
) where
    T::Error: std::fmt::Debug,
{
    if !pages.contains(&p.offset) {
        pages.insert(p.offset);
        writeln!(
            buf,
            "subgraph cluster{} {{\nlabel=\"Page {}, rc \
             {}\";\ncolor=black;",
            p.offset,
            p.offset,
            txn.rc(p.offset).unwrap()
        )
        .unwrap();
        let mut h = Vec::new();
        let mut edges = Vec::new();
        print_cursor::<T, K, V, P>(txn, buf, &mut edges, &mut h, p);
        writeln!(buf, "}}").unwrap();
        for p in edges.iter() {
            writeln!(buf, "{}", p).unwrap()
        }
        if print_children {
            for p in h.iter() {
                print_page::<T, K, V, P>(txn, pages, buf, &p.as_page(), print_children)
            }
        }
    }
}
fn print_cursor<
    T: LoadPage,
    K: Representable + ?Sized + std::fmt::Debug,
    V: Representable + ?Sized + std::fmt::Debug,
    P: btree::BTreePage<K, V>,
>(
    txn: &T,
    buf: &mut dyn std::io::Write,
    edges: &mut Vec<String>,
    pages: &mut Vec<CowPage>,
    p: &Page,
) where
    T::Error: std::fmt::Debug,
{
    let mut cursor = P::first_cursor(*p);
    let mut i = 0;
    let l = P::left_child(*p, &cursor);
    if l > 0 {
        pages.push(txn.load_page(l).unwrap());
        edges.push(format!(
            "n_{}_{}->n_{}_0[color=\"ForestGreen\"];",
            p.offset, i, l
        ))
    }
    while let Some((key, _, r)) = P::next(txn, *p, &mut cursor) {
        if i > 0 {
            writeln!(
                buf,
                "n_{}_{}->n_{}_{}[color=\"blue\"];",
                p.offset,
                i - 1,
                p.offset,
                i
            )
            .unwrap();
        }
        writeln!(buf, "n_{}_{}[label=\"{}: {:?}\"];", p.offset, i, i, key).unwrap();
        if r > 0 {
            pages.push(txn.load_page(r).unwrap());
            edges.push(format!("n_{}_{}->n_{}_0[color=\"red\"];", p.offset, i, r))
        };
        i += 1
    }
}