import type { AssignmentNode } from 'mathjs';
import type { Result } from './interface.js';
import { migrateAtomic } from './node.js';
import { migrateSymbolName, symbolName, unsupportedNode } from './utils.js';
import { migrateAccess } from './access.js';
import type { State } from './state.js';

/** 转换赋值语句 */
export function migrateAssignment(state: State, node: AssignmentNode, isTopLevel: boolean): Result {
    const { object, index, value } = node;
    const name = symbolName(object);
    if (name && index == null) {
        // Create local variable
        if (!isTopLevel) {
            return unsupportedNode(state, node, '不支持在表达式中创建局部变量');
        }
        const localName = migrateSymbolName(name, true);
        if (state.locals.has(name)) {
            state.err(`不支持局部变量重新赋值: '${name}'`);
            return {
                code: `${localName} = ${migrateAtomic(state, value).code}`,
            };
        }
        const expr = migrateAtomic(state, value);
        state.locals.set(name, expr);
        if (name !== localName) {
            state.warn(`变量名 '${name}' 是 MiraScript 关键字，已转换为 '${localName}'`);
        }
        return {
            code: `let ${localName} = ${expr.code};`,
        };
    }
    if (index != null) {
        // Assignment to array/object element
        state.loose();
        const access = migrateAccess(state, node);
        const expr = migrateAtomic(state, value);
        if (isTopLevel) {
            return { code: `${access.code} = ${expr.code};` };
        }
        return {
            // Return the assigned value
            code: `{ let ret = ${expr.code}; ${access.code} = ret; ret }`,
            type: expr.type,
        };
    }
    return unsupportedNode(state, node);
}