// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module c

import v.ast
import v.token

fn (g &Gen) defer_flag_var(stmt &ast.DeferStmt) string {
	return '${g.last_fn_c_name}_defer_${stmt.idx_in_fn}'
}

fn (g &Gen) innermost_active_defer_scope(pos token.Pos) &ast.Scope {
	pos_i := pos.pos
	mut scope := g.cur_fn.scope
	for defer_stmt in g.defer_stmts {
		if defer_stmt.scope == unsafe { nil } {
			continue
		}
		if defer_stmt.scope.start_pos <= pos_i && pos_i <= defer_stmt.scope.end_pos
			&& defer_stmt.scope.start_pos >= scope.start_pos
			&& defer_stmt.scope.end_pos <= scope.end_pos {
			scope = defer_stmt.scope
		}
	}
	return scope
}

// this function is called at the end of each block (`for`, `if` branches,
// `match` branches, etc.)
fn (mut g Gen) write_defer_stmts(scope &ast.Scope, lookup bool, pos token.Pos) {
	if scope == unsafe { nil } {
		// this should never happen
		g.error('Gen.write_defer_stmts() has received a scope that is nil', pos)
	}

	prev_inside_defer_generation := g.inside_defer_generation
	g.inside_defer_generation = true
	defer {
		g.inside_defer_generation = prev_inside_defer_generation
	}
	g.indent++
	for i := g.defer_stmts.len - 1; i >= 0; i-- {
		defer_stmt := g.defer_stmts[i]
		if defer_stmt.scope == unsafe { nil } {
			// this should never happen
			g.error('Gen.write_defer_stmts(): defer_stmt.scope is nil', pos)
		}

		if defer_stmt.mode == .scoped {
			if !((lookup && defer_stmt.scope.start_pos < scope.start_pos
				&& defer_stmt.scope.end_pos > scope.end_pos)
				|| defer_stmt.scope == scope) {
				// generate only `defer`s of the current scope (and previous ones if necessary)
				continue
			}
			g.writeln('{ // defer begin')
		} else {
			if scope != g.cur_fn.scope && !lookup {
				continue
			}
			g.writeln('if (${g.defer_flag_var(defer_stmt)}) { // defer begin')
		}

		if defer_stmt.ifdef.len > 0 {
			g.writeln(defer_stmt.ifdef)
			g.stmts(defer_stmt.stmts)
			g.writeln2('', '#endif')
		} else {
			g.stmts(defer_stmt.stmts)
		}
		g.writeln('} // defer end')
	}
	g.indent--
}

// this function is called when returning with `return`, or when the end of a function
// is reached.
fn (mut g Gen) write_defer_stmts_when_needed(scope &ast.Scope, lookup bool, pos token.Pos) {
	// unlock all mutexes, in case we are in a lock statement. defers are not
	// allowed in lock statements.
	g.unlock_locks()
	if g.defer_stmts.len > 0 {
		g.write_defer_stmts(scope, lookup, pos)
	}
	if g.defer_profile_code.len > 0 {
		g.writeln2('', '\t// defer_profile_code')
		g.writeln2(g.defer_profile_code, '')
	}
}