// Copyright (c) 2026 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
// vtest build: macos
//
// Bit-equality pin for the cursor-native rewrite of `build_as_cast_from_flat`.
// The previous helper decoded both AsCastExpr edges via `decode_expr` and
// dispatched to legacy `build_as_cast`; the cursor-native rewrite mirrors
// `build_as_cast` directly: `build_expr_from_flat(expr_c)` produces the value,
// `ast_type_to_ssa_from_flat(typ_c)` resolves the target type, and
// `get_checked_expr_type_from_flat(expr_c)` retrieves the checked source type
// (only consulted for the sumtype-source branch). This pin uses a same-type
// passthrough cast so legacy + flat both take the `values[val].typ ==
// target_type` short-circuit and emit identical IR.
module ssa

import v2.ast
import v2.types

fn ac_ident(name string) ast.Expr {
    return ast.Expr(ast.Ident{
        name: name
    })
}

fn ac_num(value string) ast.Expr {
    return ast.Expr(ast.BasicLiteral{
        kind:  .number
        value: value
    })
}

fn make_as_cast_fixture() []ast.File {
    mut stmts := [
        ast.Stmt(ast.ModuleStmt{
            name: 'main'
        }),
    ]
    // fn passthrough() i64 { x := i64(7) return x as i64 }
    stmts << ast.Stmt(ast.FnDecl{
        name:  'passthrough'
        typ:   ast.FnType{
            return_type: ac_ident('i64')
        }
        stmts: [
            ast.Stmt(ast.AssignStmt{
                op:  .decl_assign
                lhs: [ac_ident('x')]
                rhs: [ast.Expr(ast.CastExpr{
                    typ:  ac_ident('i64')
                    expr: ac_num('7')
                })]
            }),
            ast.Stmt(ast.ReturnStmt{
                exprs: [
                    ast.Expr(ast.AsCastExpr{
                        expr: ac_ident('x')
                        typ:  ac_ident('i64')
                    }),
                ]
            }),
        ]
    })
    return [
        ast.File{
            name:  'main.v'
            mod:   'main'
            stmts: stmts
        },
    ]
}

fn build_via_legacy_as_cast(files []ast.File, env &types.Environment, name string) &Module {
    mut mod := Module.new(name)
    mut b := Builder.new_with_env(mod, env)
    b.register_fn_signatures(files[0])
    b.build_fn_bodies(files[0])
    return mod
}

fn build_via_flat_as_cast(files []ast.File, env &types.Environment, name string) &Module {
    flat := ast.flatten_files(files)
    mut mod := Module.new(name)
    mut b := Builder.new_with_env(mod, env)
    b.register_fn_signatures_from_flat(flat.file_cursor(0))
    b.build_fn_bodies_from_flat(flat.file_cursor(0))
    return mod
}

fn test_build_as_cast_from_flat_matches_legacy() {
    files := make_as_cast_fixture()
    env := types.Environment.new()
    mod_legacy := build_via_legacy_as_cast(files, env, 'as_cast_legacy')
    mod_flat := build_via_flat_as_cast(files, env, 'as_cast_flat')

    assert mod_legacy.funcs.len == mod_flat.funcs.len
    assert mod_legacy.blocks.len == mod_flat.blocks.len
    assert mod_legacy.instrs.len == mod_flat.instrs.len
    assert mod_legacy.values.len == mod_flat.values.len
}