extern crate std;

use crate::*;
use std::vec;
use std::vec::Vec;

/// Fast enough for tests; the real ones are `KdfParams::DEFAULT`.
const FAST: KdfParams = KdfParams {
    memory_kib: 8,
    passes: 1,
};

/// A deterministic stand-in for the hardware's randomness.
struct Counter(u8);

impl Random for Counter {
    fn fill(&mut self, buf: &mut [u8]) -> bool {
        for b in buf {
            self.0 = self.0.wrapping_mul(31).wrapping_add(7);
            *b = self.0;
        }
        true
    }
}

struct Broken;

impl Random for Broken {
    fn fill(&mut self, _buf: &mut [u8]) -> bool {
        false
    }
}

fn memory() -> Vec<Block> {
    vec![Block::default(); FAST.memory_kib as usize]
}

fn setup(duress: Option<&[u8]>, seed: u8) -> (Record, Key) {
    Record::setup(b"1234", duress, 5, FAST, &mut memory(), &mut Counter(seed)).unwrap()
}

#[test]
fn the_real_passcode_opens_the_master_key_and_nothing_else_does() {
    let (record, master) = setup(Some(b"0000"), 1);
    let mem = &mut memory();
    assert_eq!(record.unlock(b"1234", mem), Outcome::Real(master));
    assert_eq!(record.unlock(b"0000", mem), Outcome::Duress);
    for wrong in [&b"1235"[..], b"", b"12345", b"123"] {
        assert_eq!(record.unlock(wrong, mem), Outcome::Wrong, "{wrong:?}");
    }
}

#[test]
fn without_a_duress_passcode_its_slot_opens_for_nothing() {
    let (record, master) = setup(None, 2);
    let mem = &mut memory();
    assert_eq!(record.unlock(b"1234", mem), Outcome::Real(master));
    assert_eq!(record.unlock(b"0000", mem), Outcome::Wrong);
    assert_eq!(
        record.unlock(b"", mem),
        Outcome::Wrong,
        "not even an empty one"
    );
}

#[test]
fn which_slot_is_real_is_not_fixed() {
    // Different randomness puts the real slot first in some setups, second
    // in others: its position gives nothing away.
    let mem = &mut memory();
    let mut firsts = [false; 2];
    for seed in 0..16 {
        let (record, _) = setup(Some(b"0000"), seed);
        let only_first = Record {
            slots: [record.slots[0], Slot(record.slots[1].0.map(|b| !b))],
            ..record
        };
        firsts[matches!(only_first.unlock(b"1234", mem), Outcome::Real(_)) as usize] = true;
    }
    assert_eq!(firsts, [true, true]);
}

#[test]
fn records_round_trip_and_damage_is_detected() {
    let (record, _) = setup(Some(b"0000"), 3);
    let bytes = record.encode();
    assert_eq!(Record::decode(&bytes), Some(record));
    for at in [0, 9, 18, 40, 200] {
        let mut torn = bytes;
        torn[at] ^= 1;
        assert_eq!(Record::decode(&torn), None, "byte {at}");
    }
    assert_eq!(
        Record::decode(&[0; RECORD_SIZE]),
        None,
        "a blank device holds no record"
    );
}

#[test]
fn the_newest_whole_copy_wins_and_writes_go_to_the_other() {
    let (old, _) = setup(None, 4);
    let new = old.next(|r| r.failures = 1);
    let (a, b) = (old.encode(), new.encode());
    let copies = Copies { copies: [&a, &b] };
    assert_eq!(copies.newest(), Some((new, 1)));
    assert_eq!(copies.next_copy(), 0, "the older copy is overwritten");
    // A torn write of the newer copy leaves the older one.
    let mut torn = b;
    torn[100] ^= 0xFF;
    let copies = Copies {
        copies: [&a, &torn],
    };
    assert_eq!(copies.newest(), Some((old, 0)));
    assert_eq!(copies.next_copy(), 1);
    // Newest wins wherever it is.
    let copies = Copies { copies: [&b, &a] };
    assert_eq!(copies.newest(), Some((new, 0)));
    let blank = [0u8; RECORD_SIZE];
    assert_eq!(
        Copies {
            copies: [&blank, &blank]
        }
        .newest(),
        None
    );
}

#[test]
fn wiping_leaves_nothing_any_passcode_opens() {
    let (record, _) = setup(Some(b"0000"), 5);
    let wiped = record.wiping(&mut Counter(99)).unwrap();
    assert_eq!(wiped.state, State::Wiping);
    assert!(
        wiped.must_wipe(),
        "an interrupted wipe is finished next boot"
    );
    assert!(
        wiped.generation > record.generation,
        "it is the newest copy"
    );
    let mem = &mut memory();
    for p in [&b"1234"[..], b"0000"] {
        assert_eq!(wiped.unlock(p, mem), Outcome::Wrong);
    }
}

#[test]
fn too_many_failures_mean_a_wipe() {
    let (record, _) = setup(None, 6);
    assert!(!record.must_wipe());
    let worn = record.next(|r| r.failures = r.threshold);
    assert!(worn.must_wipe());
}

#[test]
fn no_randomness_means_no_keystore() {
    assert!(Record::setup(b"1234", None, 5, FAST, &mut memory(), &mut Broken).is_none());
}

#[test]
fn the_default_parameters_are_accepted_by_argon2() {
    assert!(
        argon2::Params::new(
            KdfParams::DEFAULT.memory_kib,
            KdfParams::DEFAULT.passes,
            1,
            Some(KEY_SIZE)
        )
        .is_ok()
    );
}