module c

import v3.flat
import v3.types

// gen_string_interp emits string interp output for c.
fn (mut g FlatGen) gen_string_interp(node flat.Node) {
    n := node.children_count
    if n == 0 {
        sid := g.intern_string('')
        g.write('_str_${sid}')
        return
    }
    g.write('string_plus_many(${n}, (string[${n}]){')
    for i in 0 .. n {
        if i > 0 {
            g.write(', ')
        }
        child_id := g.a.child(&node, i)
        child := g.a.nodes[int(child_id)]
        if child.kind == .string_literal {
            sid := g.intern_string(child.value)
            g.write('_str_${sid}')
        } else if child.typ == 'string' {
            g.gen_expr(child_id)
        } else {
            mut typ := g.tc.resolve_type(child_id)
            // For a bare ident, prefer the live cgen scope binding when present: it reflects
            // locals introduced during generation (e.g. the `err` of an or-body lowered here,
            // or for-loop vars) that resolve_type may stale-cache as `int`.
            if child.kind == .ident {
                if scope_typ := g.tc.cur_scope.lookup(child.value) {
                    if scope_typ !is types.Void {
                        typ = scope_typ
                    }
                }
            }
            typ_name := types.Type(typ).name()
            if typ is types.String {
                g.gen_expr(child_id)
            } else if typ_name == 'IError' || typ_name.ends_with('.IError') {
                // IError may resolve as Interface/Alias/Struct depending on context; match by
                // name and interpolate its `.message` (mirrors the transformer's IError path).
                g.gen_expr(child_id)
                g.write('.message')
            } else if typ is types.Primitive {
                prim_name := types.Type(typ).name()
                g.write('${c_name('${prim_name}.str')}(')
                g.gen_expr(child_id)
                g.write(')')
            } else if typ is types.ISize || typ is types.USize {
                g.write('${c_name('${typ.name()}.str')}(')
                g.gen_expr(child_id)
                g.write(')')
            } else if typ is types.Struct {
                g.write('${c_name(typ.name)}__str(')
                g.gen_expr(child_id)
                g.write(')')
            } else if typ is types.SumType {
                g.write('${c_name(typ.name)}__str(')
                g.gen_expr(child_id)
                g.write(')')
            } else {
                g.write('int__str(')
                g.gen_expr(child_id)
                g.write(')')
            }
        }
    }
    g.write('})')
}

// is_string_node reports whether is string node applies in c.
fn (g &FlatGen) is_string_node(id flat.NodeId) bool {
    return g.tc.resolve_type(id) is types.String
}

// string_literals supports string literals handling for FlatGen.
fn (mut g FlatGen) string_literals() {
    for i, s in g.str_lits {
        escaped := s.replace('\\', '\\\\').replace('"', '\\"').replace('\n', '\\n').replace('\t',
            '\\t').replace('\r', '\\r')
        g.writeln('string _str_${i} = {"${escaped}", ${s.len}, 1};')
    }
    if g.str_lits.len > 0 {
        g.writeln('')
    }
}

// intern_string supports intern string handling for FlatGen.
fn (mut g FlatGen) intern_string(s string) int {
    if s in g.str_lit_ids {
        return g.str_lit_ids[s]
    }
    id := g.str_lits.len
    g.str_lits << s
    g.str_lit_ids[s] = id
    return id
}