// Tests for lower.zig

const std = @import("std");
const ast = @import("../ast.zig");
const Node = ast.Node;

const ir_mod = @import("ir.zig");
const TypeId = ir_mod.TypeId;
const Ref = ir_mod.Ref;
const FuncId = ir_mod.FuncId;
const Lowering = ir_mod.Lowering;

test "lower: simple function with arithmetic" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();

    // Build a minimal AST: add :: (a: s64, b: s64) -> s64 { return a + b; }
    const a_type = alloc.create(Node) catch unreachable;
    a_type.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .type_expr = .{ .name = "s64", .is_generic = false } } };
    const b_type = alloc.create(Node) catch unreachable;
    b_type.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .type_expr = .{ .name = "s64", .is_generic = false } } };
    const ret_type = alloc.create(Node) catch unreachable;
    ret_type.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .type_expr = .{ .name = "s64", .is_generic = false } } };

    const a_ident = alloc.create(Node) catch unreachable;
    a_ident.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .identifier = .{ .name = "a" } } };
    const b_ident = alloc.create(Node) catch unreachable;
    b_ident.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .identifier = .{ .name = "b" } } };

    const add_expr = alloc.create(Node) catch unreachable;
    add_expr.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .binary_op = .{
        .op = .add,
        .lhs = a_ident,
        .rhs = b_ident,
    } } };

    const ret_stmt = alloc.create(Node) catch unreachable;
    ret_stmt.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .return_stmt = .{ .value = add_expr } } };

    const body = alloc.create(Node) catch unreachable;
    const stmts: []const *Node = &.{ret_stmt};
    body.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .block = .{ .stmts = stmts } } };

    defer alloc.destroy(a_type);
    defer alloc.destroy(b_type);
    defer alloc.destroy(ret_type);
    defer alloc.destroy(a_ident);
    defer alloc.destroy(b_ident);
    defer alloc.destroy(add_expr);
    defer alloc.destroy(ret_stmt);
    defer alloc.destroy(body);

    const params: []const ast.Param = &.{
        .{ .name = "a", .name_span = .{ .start = 0, .end = 0 }, .type_expr = a_type },
        .{ .name = "b", .name_span = .{ .start = 0, .end = 0 }, .type_expr = b_type },
    };

    const fn_decl = ast.FnDecl{
        .name = "add",
        .params = params,
        .return_type = ret_type,
        .body = body,
    };

    var lowering = Lowering.init(&module);
    lowering.lowerFunction(&fn_decl, "add");

    // Verify
    try std.testing.expectEqual(@as(usize, 1), module.functions.items.len);
    const func = module.getFunction(FuncId.fromIndex(0));
    try std.testing.expectEqual(@as(usize, 2), func.params.len);
    try std.testing.expectEqual(TypeId.s64, func.ret);
    try std.testing.expect(func.blocks.items.len > 0);

    // Print the IR to verify it looks reasonable
    const print_mod = @import("print.zig");
    var aw = std.Io.Writer.Allocating.init(alloc);
    try print_mod.printModule(&module, &aw.writer);
    var result = aw.writer.toArrayList();
    defer result.deinit(alloc);

    const output = result.items;
    try std.testing.expect(std.mem.indexOf(u8, output, "func @add") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "entry:") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "add %") != null or std.mem.indexOf(u8, output, "ret %") != null);
}

test "lower: if/else generates basic blocks" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();

    // Build AST: test :: () -> s64 { if true { return 1; } else { return 2; } }
    const cond_node = alloc.create(Node) catch unreachable;
    defer alloc.destroy(cond_node);
    cond_node.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .bool_literal = .{ .value = true } } };

    const ret1_val = alloc.create(Node) catch unreachable;
    defer alloc.destroy(ret1_val);
    ret1_val.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .int_literal = .{ .value = 1 } } };

    const ret2_val = alloc.create(Node) catch unreachable;
    defer alloc.destroy(ret2_val);
    ret2_val.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .int_literal = .{ .value = 2 } } };

    const then_ret = alloc.create(Node) catch unreachable;
    defer alloc.destroy(then_ret);
    then_ret.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .return_stmt = .{ .value = ret1_val } } };

    const else_ret = alloc.create(Node) catch unreachable;
    defer alloc.destroy(else_ret);
    else_ret.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .return_stmt = .{ .value = ret2_val } } };

    const then_body = alloc.create(Node) catch unreachable;
    defer alloc.destroy(then_body);
    then_body.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .block = .{ .stmts = &.{then_ret} } } };

    const else_body = alloc.create(Node) catch unreachable;
    defer alloc.destroy(else_body);
    else_body.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .block = .{ .stmts = &.{else_ret} } } };

    const if_node = alloc.create(Node) catch unreachable;
    defer alloc.destroy(if_node);
    if_node.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .if_expr = .{
        .condition = cond_node,
        .then_branch = then_body,
        .else_branch = else_body,
        .is_inline = false,
    } } };

    const fn_body = alloc.create(Node) catch unreachable;
    defer alloc.destroy(fn_body);
    fn_body.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .block = .{ .stmts = &.{if_node} } } };

    const ret_type = alloc.create(Node) catch unreachable;
    defer alloc.destroy(ret_type);
    ret_type.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .type_expr = .{ .name = "s64", .is_generic = false } } };

    const fn_decl = ast.FnDecl{
        .name = "test_if",
        .params = &.{},
        .return_type = ret_type,
        .body = fn_body,
    };

    var lowering = Lowering.init(&module);
    lowering.lowerFunction(&fn_decl, "test_if");

    // Verify: should have 4 blocks (entry, if.then, if.else, if.merge)
    const func = module.getFunction(FuncId.fromIndex(0));
    try std.testing.expectEqual(@as(usize, 4), func.blocks.items.len);

    // Print and verify structure
    const print_mod = @import("print.zig");
    var aw = std.Io.Writer.Allocating.init(alloc);
    try print_mod.printModule(&module, &aw.writer);
    var result = aw.writer.toArrayList();
    defer result.deinit(alloc);
    const output = result.items;

    try std.testing.expect(std.mem.indexOf(u8, output, "cond_br") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "if.then") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "if.else") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "if.merge") != null);
}

test "lower: while loop generates header/body/exit blocks" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();

    // Build AST: loop :: () { while true { break; } }
    const cond_node = alloc.create(Node) catch unreachable;
    defer alloc.destroy(cond_node);
    cond_node.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .bool_literal = .{ .value = true } } };

    const break_node = alloc.create(Node) catch unreachable;
    defer alloc.destroy(break_node);
    break_node.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .break_expr };

    const while_body = alloc.create(Node) catch unreachable;
    defer alloc.destroy(while_body);
    while_body.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .block = .{ .stmts = &.{break_node} } } };

    const while_node = alloc.create(Node) catch unreachable;
    defer alloc.destroy(while_node);
    while_node.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .while_expr = .{
        .condition = cond_node,
        .body = while_body,
    } } };

    const fn_body = alloc.create(Node) catch unreachable;
    defer alloc.destroy(fn_body);
    fn_body.* = .{ .span = .{ .start = 0, .end = 0 }, .data = .{ .block = .{ .stmts = &.{while_node} } } };

    const fn_decl = ast.FnDecl{
        .name = "loop_test",
        .params = &.{},
        .return_type = null,
        .body = fn_body,
    };

    var lowering = Lowering.init(&module);
    lowering.lowerFunction(&fn_decl, "loop_test");

    // Verify: should have 4 blocks (entry, while.hdr, while.body, while.exit)
    const func = module.getFunction(FuncId.fromIndex(0));
    try std.testing.expectEqual(@as(usize, 4), func.blocks.items.len);

    // Print and verify structure
    const print_mod = @import("print.zig");
    var aw = std.Io.Writer.Allocating.init(alloc);
    try print_mod.printModule(&module, &aw.writer);
    var result = aw.writer.toArrayList();
    defer result.deinit(alloc);
    const output = result.items;

    try std.testing.expect(std.mem.indexOf(u8, output, "while.hdr") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "while.body") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "while.exit") != null);
    try std.testing.expect(std.mem.indexOf(u8, output, "cond_br") != null);
}

// M1.2 A.1 — Obj-C type-encoding helper.
test "lower: objcTypeEncodingFromSignature emits primitive shapes" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();
    var lowering = Lowering.init(&module);

    // Niladic void method: -(void)greet  →  "v@:"
    const e1 = try lowering.objcTypeEncodingFromSignature(.void, &.{}, null);
    defer alloc.free(e1);
    try std.testing.expectEqualStrings("v@:", e1);

    // Returns s32, takes s32: -(int)add:(int)x  →  "i@:i"
    const e2 = try lowering.objcTypeEncodingFromSignature(.s32, &.{.s32}, null);
    defer alloc.free(e2);
    try std.testing.expectEqualStrings("i@:i", e2);

    // s64 return, two s64 args: "q@:qq"
    const e3 = try lowering.objcTypeEncodingFromSignature(.s64, &.{ .s64, .s64 }, null);
    defer alloc.free(e3);
    try std.testing.expectEqualStrings("q@:qq", e3);

    // BOOL return (s8): "c@:"
    const e4 = try lowering.objcTypeEncodingFromSignature(.s8, &.{}, null);
    defer alloc.free(e4);
    try std.testing.expectEqualStrings("c@:", e4);

    // Float/double: "f@:d"
    const e5 = try lowering.objcTypeEncodingFromSignature(.f32, &.{.f64}, null);
    defer alloc.free(e5);
    try std.testing.expectEqualStrings("f@:d", e5);

    // bool (i1) is `B` — distinct from BOOL (`c`).
    const e6 = try lowering.objcTypeEncodingFromSignature(.bool, &.{.bool}, null);
    defer alloc.free(e6);
    try std.testing.expectEqualStrings("B@:B", e6);

    // usize / isize on the 64-bit target.
    const e7 = try lowering.objcTypeEncodingFromSignature(.usize, &.{.isize}, null);
    defer alloc.free(e7);
    try std.testing.expectEqualStrings("Q@:q", e7);

    // Unsigned variants u8/u16/u32/u64.
    const e8 = try lowering.objcTypeEncodingFromSignature(.u32, &.{ .u8, .u16, .u64 }, null);
    defer alloc.free(e8);
    try std.testing.expectEqualStrings("I@:CSQ", e8);
}

test "lower: objcTypeEncodingFromSignature emits pointer shapes" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();
    var lowering = Lowering.init(&module);

    // Generic `*void` → `^v`.
    const void_ptr = module.types.ptrTo(.void);
    const e1 = try lowering.objcTypeEncodingFromSignature(void_ptr, &.{void_ptr}, null);
    defer alloc.free(e1);
    try std.testing.expectEqualStrings("^v@:^v", e1);

    // `[*]u8` C-string carrier → `*`.
    const u8_many = module.types.intern(.{ .many_pointer = .{ .element = .u8 } });
    const e2 = try lowering.objcTypeEncodingFromSignature(.void, &.{u8_many}, null);
    defer alloc.free(e2);
    try std.testing.expectEqualStrings("v@:*", e2);

    // `[*]s32` (non-u8 many-pointer) → `^v`.
    const s32_many = module.types.intern(.{ .many_pointer = .{ .element = .s32 } });
    const e3 = try lowering.objcTypeEncodingFromSignature(.void, &.{s32_many}, null);
    defer alloc.free(e3);
    try std.testing.expectEqualStrings("v@:^v", e3);
}

// M1.2 A.2 — sx-defined #objc_class state struct construction.
test "lower: objcDefinedStateStructType collects user-declared fields" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();
    var lowering = Lowering.init(&module);

    // Synthesize a #objc_class("SxFoo") { counter: s32; ticks: s64; } AST.
    const span = ast.Span{ .start = 0, .end = 0 };
    const counter_type = try alloc.create(Node);
    defer alloc.destroy(counter_type);
    counter_type.* = .{ .span = span, .data = .{ .type_expr = .{ .name = "s32", .is_generic = false } } };
    const ticks_type = try alloc.create(Node);
    defer alloc.destroy(ticks_type);
    ticks_type.* = .{ .span = span, .data = .{ .type_expr = .{ .name = "s64", .is_generic = false } } };

    const members = [_]ast.ForeignClassMember{
        .{ .field = .{ .name = "counter", .field_type = counter_type } },
        .{ .field = .{ .name = "ticks", .field_type = ticks_type } },
    };
    const fcd = ast.ForeignClassDecl{
        .name = "SxFoo",
        .foreign_path = "SxFoo",
        .runtime = .objc_class,
        .members = &members,
        .is_foreign = false,
        .is_main = false,
    };

    const state_ty = lowering.objcDefinedStateStructType(&fcd);
    const info = module.types.get(state_ty);
    try std.testing.expectEqual(@as(std.meta.Tag(@TypeOf(info)), .@"struct"), std.meta.activeTag(info));

    const s = info.@"struct";
    try std.testing.expectEqualStrings("__SxFooState", module.types.getString(s.name));
    try std.testing.expectEqual(@as(usize, 2), s.fields.len);
    try std.testing.expectEqualStrings("counter", module.types.getString(s.fields[0].name));
    try std.testing.expectEqual(TypeId.s32, s.fields[0].ty);
    try std.testing.expectEqualStrings("ticks", module.types.getString(s.fields[1].name));
    try std.testing.expectEqual(TypeId.s64, s.fields[1].ty);

    // Idempotency: a second call returns the same TypeId (cache hit on name).
    const state_ty2 = lowering.objcDefinedStateStructType(&fcd);
    try std.testing.expectEqual(state_ty, state_ty2);
}

test "lower: objcDefinedStateStructType handles empty field set" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();
    var lowering = Lowering.init(&module);

    const fcd = ast.ForeignClassDecl{
        .name = "SxEmpty",
        .foreign_path = "SxEmpty",
        .runtime = .objc_class,
        .members = &.{},
        .is_foreign = false,
        .is_main = false,
    };

    const state_ty = lowering.objcDefinedStateStructType(&fcd);
    const info = module.types.get(state_ty);
    try std.testing.expectEqualStrings("__SxEmptyState", module.types.getString(info.@"struct".name));
    try std.testing.expectEqual(@as(usize, 0), info.@"struct".fields.len);
}

test "lower: objcDefinedStateStructType skips non-field members" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();
    var lowering = Lowering.init(&module);

    // Mix in #extends and method members — only `.field` contributes.
    const span = ast.Span{ .start = 0, .end = 0 };
    const counter_type = try alloc.create(Node);
    defer alloc.destroy(counter_type);
    counter_type.* = .{ .span = span, .data = .{ .type_expr = .{ .name = "s32", .is_generic = false } } };

    const members = [_]ast.ForeignClassMember{
        .{ .extends = "NSObject" },
        .{ .field = .{ .name = "counter", .field_type = counter_type } },
        .{ .implements = "UIApplicationDelegate" },
    };
    const fcd = ast.ForeignClassDecl{
        .name = "SxMixed",
        .foreign_path = "SxMixed",
        .runtime = .objc_class,
        .members = &members,
        .is_foreign = false,
        .is_main = false,
    };

    const state_ty = lowering.objcDefinedStateStructType(&fcd);
    const info = module.types.get(state_ty);
    try std.testing.expectEqual(@as(usize, 1), info.@"struct".fields.len);
    try std.testing.expectEqualStrings("counter", module.types.getString(info.@"struct".fields[0].name));
}

test "lower: objcTypeEncodingFromSignature emits @ for Obj-C class pointers" {
    const alloc = std.testing.allocator;
    var module = ir_mod.Module.init(alloc);
    defer module.deinit();
    var lowering = Lowering.init(&module);

    // Synthesize a foreign Obj-C class entry so the encoder recognises
    // `*NSString` as an object pointer.
    const ns_name = module.types.internString("NSString");
    const ns_struct = module.types.intern(.{ .@"struct" = .{ .name = ns_name, .fields = &.{} } });
    const ns_ptr = module.types.ptrTo(ns_struct);
    var ns_fcd = ast.ForeignClassDecl{
        .name = "NSString",
        .foreign_path = "NSString",
        .runtime = .objc_class,
        .members = &.{},
        .is_foreign = true,
        .is_main = false,
    };
    try lowering.foreign_class_map.put("NSString", &ns_fcd);

    // Return *NSString, no args: "@@:"
    const e1 = try lowering.objcTypeEncodingFromSignature(ns_ptr, &.{}, null);
    defer alloc.free(e1);
    try std.testing.expectEqualStrings("@@:", e1);

    // Return *NSString, take *NSString: "@@:@"
    const e2 = try lowering.objcTypeEncodingFromSignature(ns_ptr, &.{ns_ptr}, null);
    defer alloc.free(e2);
    try std.testing.expectEqualStrings("@@:@", e2);
}