// Expect retcode = 0

// 开放寻址集合。键按字节复制到集合自己的存储中；集合只释放自身存储，
// 不释放键值内部引用的资源。哈希与相等回调的约定和 Map 一致。
type .{ .Status } = @import("error.spl");
type .{ .Map, .LookupResult, .hash_kind_usize, .hash_kind_view, .hash_kind_constant } =
    @import("map.spl");
type .{ .ByteView } = @import("byte_view.spl");
type .{ .hash_usize, .eq_usize, .hash_view, .eq_view } = @import("hash.spl");

type Set = @self;

map: Map,

fn new(key_size: usize, key_align: usize, hash_kind: usize): Set {
    ret Set {
        .map = Map.new(key_size, key_align, 1, 1, hash_kind),
    };
}

fn valid(self: Set): bool {
    ret Map.valid(&self.map) && self.map.val_size == 1;
}

fn size(self: Set): usize {
    ret self.map.size;
}

fn capacity(self: Set): usize {
    ret self.map.states.cap;
}

fn reserve(self: *Set, need: usize): Status {
    ret Map.reserve(&self.map, need);
}

// 重复插入保持集合大小不变。
fn insert(self: *Set, key: *u8): Status {
    var marker: u8 = 1;
    ret Map.put(&self.map, key, &marker);
}

fn find(self: *Set, key: *u8): LookupResult {
    var marker: u8 = 0;
    ret Map.get(&self.map, key, &marker);
}

fn remove(self: *Set, key: *u8): LookupResult {
    ret Map.del(&self.map, key);
}

// 遍历 [0, slot_count)；仅 slot_occupied 为真时 key_at 有效。
fn slot_count(self: Set): usize {
    ret Map.slot_count(self.map);
}

fn slot_occupied(self: Set, index: usize): bool {
    ret Map.slot_occupied(Map.slot_state(self.map, index));
}

fn key_at(self: *Set, index: usize): *u8 {
    ret Map.key_at(&self.map, index);
}

fn clear(self: *Set) {
    Map.clear(&self.map);
}

fn take(source: *Set): Set {
    ret Set { .map = Map.take(&source.map) };
}

fn drop(self: *Set) {
    Map.drop(&self.map);
}

// ---- 测试 ----

fn expect_ok(result: Status) {
    match result {
        .Ok => {},
        .Err(error) => { @assert(false, "unexpected Set error"); },
    }
}

fn found(set: *Set, key: *u8): bool {
    match find(set, key) {
        .Found => { ret true; },
        .NotFound => { ret false; },
    }
    ret false;
}

fn removed(set: *Set, key: *u8): bool {
    match remove(set, key) {
        .Found => { ret true; },
        .NotFound => { ret false; },
    }
    ret false;
}

fn constant_hash(key: *u8): usize {
    ret 3;
}

fn test_insert_find_remove() {
    var set = new(@sizeof(usize), @alignof(usize), hash_kind_usize());
    defer { drop(&set); }
    @assert(valid(set));
    @assert(size(set) == 0 && capacity(set) == 0);

    var i: usize = 0;
    while i < 1000 {
        expect_ok(insert(&set, &i as *u8));
        i = i + 1;
    }
    @assert(size(set) == 1000, "all unique keys inserted");

    i = 0;
    while i < 1000 {
        @assert(found(&set, &i as *u8), "key survives growth");
        i = i + 1;
    }

    // 重复键不增加 size。
    i = 0;
    while i < 1000 {
        expect_ok(insert(&set, &i as *u8));
        i = i + 1;
    }
    @assert(size(set) == 1000, "duplicate insertion is idempotent");

    i = 0;
    while i < 1000 {
        if i % 2 == 0 { @assert(removed(&set, &i as *u8)); }
        i = i + 1;
    }
    @assert(size(set) == 500);

    i = 0;
    while i < 1000 {
        @assert(found(&set, &i as *u8) == (i % 2 != 0), "removed membership");
        i = i + 1;
    }

    i = 0;
    while i < 1000 {
        if i % 2 == 0 { expect_ok(insert(&set, &i as *u8)); }
        i = i + 1;
    }
    @assert(size(set) == 1000, "removed keys can be reinserted");

    var occupied: usize = 0;
    i = 0;
    while i < slot_count(set) {
        if slot_occupied(set, i) {
            var key = (key_at(&set, i) as *usize).*;
            @assert(key < 1000, "iteration yields stored key");
            occupied = occupied + 1;
        }
        i = i + 1;
    }
    @assert(occupied == size(set), "iteration visits each member once");

    var missing: usize = 2000;
    @assert(!removed(&set, &missing as *u8));
    clear(&set);
    @assert(size(set) == 0 && capacity(set) != 0, "clear retains allocation");
}

fn test_collisions_and_take() {
    var set = new(@sizeof(usize), @alignof(usize), hash_kind_constant());
    defer { drop(&set); }

    var i: usize = 0;
    while i < 64 {
        expect_ok(insert(&set, &i as *u8));
        i = i + 1;
    }
    i = 0;
    while i < 64 {
        @assert(found(&set, &i as *u8), "collision chain lookup");
        i = i + 1;
    }

    // 删除整条碰撞链后重新插入，验证墓碑会被复用且探测会终止。
    i = 0;
    while i < 64 {
        @assert(removed(&set, &i as *u8));
        i = i + 1;
    }
    @assert(size(set) == 0);
    i = 64;
    while i < 128 {
        expect_ok(insert(&set, &i as *u8));
        i = i + 1;
    }
    i = 64;
    while i < 128 {
        @assert(found(&set, &i as *u8), "tombstone collision chain reuse");
        i = i + 1;
    }

    var moved = take(&set);
    defer { drop(&moved); }
    @assert(size(set) == 0 && capacity(set) == 0, "take clears source");
    @assert(size(moved) == 64, "take preserves members");
    i = 64;
    while i < 128 {
        @assert(found(&moved, &i as *u8));
        i = i + 1;
    }
}

fn test_byte_view_keys() {
    var set = new(@sizeof(ByteView), @alignof(ByteView), hash_kind_view());
    defer { drop(&set); }

    var alpha = ByteView.from_slice("alpha");
    var alpha_copy = ByteView.from_slice("alpha");
    var beta = ByteView.from_slice("beta");
    expect_ok(insert(&set, &alpha as *u8));
    expect_ok(insert(&set, &alpha_copy as *u8));
    expect_ok(insert(&set, &beta as *u8));
    @assert(size(set) == 2, "ByteView keys compare by content");
    @assert(found(&set, &alpha_copy as *u8));
    @assert(removed(&set, &alpha_copy as *u8));
    @assert(!found(&set, &alpha as *u8));
}

fn main() {
    test_insert_find_remove();
    test_collisions_and_take();
    test_byte_view_keys();
}