// Expect retcode = 0

// 声明句柄表（移植自 stage1/spl_lang_type.h 的 spl_def_node_t 部分）。
// DefId 是「声明」的稳定身份：作用域符号、AST 节点 resolved_def_id、以及将来
// comptime 生成的声明都用它。前向引用/环形引用由 state 状态机表达。
//
// 与 stage1 的差异：owner_ast 改为不透明 `*any`（借用），使本表不依赖具体 AST
// 表示，便于将来 comptime/序列化复用；sema 侧自行 cast 回 *Ast。
// 名称是 ByteView（借用源/AST），本表不做拥有。

type .{ .Error } = @import("utils/error.spl");
type .{ .Vec } = @import("utils/vec.spl");
type .{ .ByteView } = @import("utils/byte_view.spl");
type .{ .ByteBuffer } = @import("utils/byte_buffer.spl");
type .{ .append_usize } = @import("utils/fmt.spl");
type .{ .Span, .span_none } = @import("./diag.spl");

type DefKind = enum {
    Error,
    Scalar,
    Member,
    Var,
    Fn,
    Agg,
    Distinct,
    Alias,
    Builtin,
}

type DeclState = enum {
    Unresolved,
    Resolving,
    Resolved,
    Error,
}

type DefNode = struct {
    kind: DefKind,
    name: ByteView,
    span: Span,
    lang_id: usize,
    owner: *any, // 借用；不透明，sema 侧 cast 回 *Ast
    ast_node_ref: usize,
    state: DeclState,
    owner_def: usize,
}

type DefTable = @self;

table: Vec, // DefNode

type DefTableResult = enum {
    Ok: DefTable,
    Err: Error,
}

fn new_node(): DefNode {
    ret DefNode {
        .kind = .Error,
        .name = ByteView.empty(),
        .span = span_none(),
        .lang_id = 0,
        .owner = null,
        .ast_node_ref = 0,
        .state = .Unresolved,
        .owner_def = 0,
    };
}

fn new(): DefTableResult {
    var dt = DefTable { .table = Vec.blank(@sizeof(DefNode), @alignof(DefNode)) };
    var sentinel = new_node();
    match Vec.push(&dt.table, &sentinel as *u8) {
        .Ok => {},
        .Err(error) => {
            Vec.drop(&dt.table);
            ret .Err(error);
        },
    }
    ret .Ok(dt);
}

fn drop(self: *DefTable) {
    Vec.drop(&self.table);
}

// id 0 与越界均返回 null（对应 stage1 spl_def_node）。
fn node(self: *DefTable, id: usize): *DefNode {
    if id == 0 || id >= self.table.len { ret null; }
    match Vec.get(&self.table, id) {
        .Ok(ptr) => { ret ptr as *DefNode; },
        .Err(error) => { ret null; },
    }
    ret null;
}

fn count(self: *DefTable): usize {
    ret self.table.len;
}

// 追加一条声明，返回其 DefId（失败返回 0）。
fn alloc(self: *DefTable, kind: DefKind, name: ByteView, span: Span, owner: *any,
         ast_node_ref: usize): usize {
    var n = new_node();
    n.kind = kind;
    n.name = name;
    n.span = span;
    n.owner = owner;
    n.ast_node_ref = ast_node_ref;
    match Vec.push(&self.table, &n as *u8) {
        .Ok => {},
        .Err(error) => { ret 0; },
    }
    ret self.table.len - 1;
}

fn resolve(self: *DefTable, id: usize, lang_id: usize) {
    var d = node(self, id);
    if d == null { ret; }
    d.lang_id = lang_id;
    d.state = .Resolved;
}

fn set_state(self: *DefTable, id: usize, state: DeclState) {
    var d = node(self, id);
    if d == null { ret; }
    d.state = state;
}

fn get_lang_id(self: *DefTable, id: usize): usize {
    var d = node(self, id);
    if d == null { ret 0; }
    ret d.lang_id;
}

// ---- 分类 ----

fn kind_name(kind: DefKind): []u8 {
    match kind {
        .Error => { ret "error"; },
        .Scalar => { ret "scalar"; },
        .Member => { ret "member"; },
        .Var => { ret "var"; },
        .Fn => { ret "fn"; },
        .Agg => { ret "agg"; },
        .Distinct => { ret "distinct"; },
        .Alias => { ret "alias"; },
        .Builtin => { ret "builtin"; },
    }
    ret "unknown";
}

fn state_name(state: DeclState): []u8 {
    match state {
        .Unresolved => { ret "unresolved"; },
        .Resolving => { ret "resolving"; },
        .Resolved => { ret "resolved"; },
        .Error => { ret "error"; },
    }
    ret "unknown";
}

// 能作为类型使用的 def（对应 stage1 sema_def_is_type）。
fn is_type_kind(kind: DefKind): bool {
    match kind {
        .Scalar => { ret true; },
        .Agg => { ret true; },
        .Distinct => { ret true; },
        .Alias => { ret true; },
        .Builtin => { ret true; },
        _ => { ret false; },
    }
    ret false;
}

// ---- dump（镜像 stage1 spl_type_def_dump 的文本）----

fn push_out(buf: *ByteBuffer, bytes: []u8): bool {
    match ByteBuffer.append(buf, bytes) {
        .Ok => { ret true; },
        .Err(error) => { ret false; },
    }
    ret false;
}

fn push_usize(buf: *ByteBuffer, value: usize): bool {
    match append_usize(buf, value, 10, false) {
        .Ok => { ret true; },
        .Err(error) => { ret false; },
    }
    ret false;
}

fn dump(self: *DefTable, id: usize, out: *ByteBuffer): bool {
    var d = node(self, id);
    if d == null {
        ret push_out(out, "none");
    }
    if !push_out(out, "kind=") { ret false; }
    if !push_out(out, kind_name(d.kind)) { ret false; }
    if !push_out(out, " lang_id=") { ret false; }
    if !push_usize(out, d.lang_id) { ret false; }
    if !push_out(out, " name=") { ret false; }
    if d.name.len == 0 {
        ret push_out(out, "?");
    }
    ret push_out(out, ByteView.as_slice(d.name));
}

// ---- 测试 ----

fn test_alloc_and_state() {
    var dt: DefTable = undefined;
    match new() {
        .Ok(v) => { dt = v; },
        .Err(error) => { @assert(false, "def table new failed"); },
    }
    defer { drop(&dt); }

    @assert(count(&dt) == 1, "sentinel only");
    @assert(node(&dt, 0) == null, "id 0 is null");

    var span = span_none();
    var a = alloc(&dt, .Fn, ByteView.from_slice("foo"), span, null, 7);
    var b = alloc(&dt, .Agg, ByteView.from_slice("Bar"), span, null, 9);
    @assert(a == 1 && b == 2, "ids increase from 1");

    var na = node(&dt, a);
    @assert(na != null, "node a");
    @assert(ByteView.eq(na.name, ByteView.from_slice("foo")), "name stored");
    @assert(na.ast_node_ref == 7, "ast_node_ref stored");
    @assert(na.owner == null, "owner stored");
    match na.state {
        .Unresolved => {},
        _ => { @assert(false, "initial state unresolved"); },
    }
    match na.kind {
        .Fn => {},
        _ => { @assert(false, "kind fn"); },
    }

    resolve(&dt, a, 42);
    @assert(get_lang_id(&dt, a) == 42, "lang id resolved");
    var na2 = node(&dt, a);
    match na2.state {
        .Resolved => {},
        _ => { @assert(false, "state resolved"); },
    }

    set_state(&dt, b, .Resolving);
    var nb = node(&dt, b);
    match nb.state {
        .Resolving => {},
        _ => { @assert(false, "state resolving"); },
    }

    @assert(get_lang_id(&dt, 999) == 0, "missing id");
}

fn test_kind_helpers() {
    @assert(is_type_kind(.Scalar), "scalar is type");
    @assert(is_type_kind(.Agg), "agg is type");
    @assert(is_type_kind(.Alias), "alias is type");
    @assert(!is_type_kind(.Fn), "fn not type");
    @assert(!is_type_kind(.Var), "var not type");
    @assert(!is_type_kind(.Member), "member not type");

    @assert(ByteView.eq(ByteView.from_slice(kind_name(.Agg)), ByteView.from_slice("agg")), "agg name");
    @assert(ByteView.eq(ByteView.from_slice(state_name(.Resolving)),
                        ByteView.from_slice("resolving")),
            "resolving name");
}

fn test_dump() {
    var dt: DefTable = undefined;
    match new() {
        .Ok(v) => { dt = v; },
        .Err(error) => { @assert(false, "def table new failed"); },
    }
    defer { drop(&dt); }

    var a = alloc(&dt, .Var, ByteView.from_slice("x"), span_none(), null, 0);
    resolve(&dt, a, 5);

    var out = ByteBuffer.new();
    defer { ByteBuffer.drop(&out); }
    if !dump(&dt, a, &out) { @assert(false, "dump ok"); }
    expect_text(out, "kind=var lang_id=5 name=x");

    var out2 = ByteBuffer.new();
    defer { ByteBuffer.drop(&out2); }
    if !dump(&dt, 0, &out2) { @assert(false, "dump none ok"); }
    expect_text(out2, "none");

    var out3 = ByteBuffer.new();
    defer { ByteBuffer.drop(&out3); }
    var c = alloc(&dt, .Alias, ByteView.empty(), span_none(), null, 0);
    if !dump(&dt, c, &out3) { @assert(false, "dump empty name ok"); }
    expect_text(out3, "kind=alias lang_id=0 name=?");
}

fn expect_text(buf: ByteBuffer, expected: []u8) {
    var got = ByteBuffer.as_slice(buf);
    @assert(got.len == expected.len, "dump length");
    var i: usize = 0;
    while i < expected.len {
        @assert(got.ptr[i] == expected.ptr[i], "dump byte");
        i = i + 1;
    }
}

fn main() {
    test_alloc_and_state();
    test_kind_helpers();
    test_dump();
}