#include "pocketpy/modules/csv.hpp"
#include "pocketpy/interpreter/bindings.hpp"

namespace pkpy {

void add_module_csv(VM* vm) {
    PyObject* mod = vm->new_module("csv");

    vm->bind(mod, "reader(csvfile: list[str]) -> list[list]", [](VM* vm, ArgsView args) {
        const List& csvfile = CAST(List&, args[0]);
        List ret;
        for(int i = 0; i < csvfile.size(); i++) {
            std::string_view line = CAST(Str&, csvfile[i]).sv();
            if(i == 0) {
                // Skip utf8 BOM if there is any.
                if(strncmp(line.data(), "\xEF\xBB\xBF", 3) == 0) {
                    line = line.substr(3);
                }
            }
            List row;
            int j;
            bool in_quote = false;
            std::string buffer;
        __NEXT_LINE:
            j = 0;
            while(j < line.size()) {
                switch(line[j]) {
                    case '"':
                        if(in_quote) {
                            if(j + 1 < line.size() && line[j + 1] == '"') {
                                buffer += '"';
                                j++;
                            } else {
                                in_quote = false;
                            }
                        } else {
                            in_quote = true;
                        }
                        break;
                    case ',':
                        if(in_quote) {
                            buffer += line[j];
                        } else {
                            row.push_back(VAR(buffer));
                            buffer.clear();
                        }
                        break;
                    case '\r': break;  // ignore
                    default: buffer += line[j]; break;
                }
                j++;
            }
            if(in_quote) {
                if(i == csvfile.size() - 1) {
                    vm->ValueError("unterminated quote");
                } else {
                    buffer += '\n';
                    i++;
                    line = CAST(Str&, csvfile[i]).sv();
                    goto __NEXT_LINE;
                }
            }
            row.push_back(VAR(buffer));
            ret.push_back(VAR(std::move(row)));
        }
        return VAR(std::move(ret));
    });

    vm->bind(mod, "DictReader(csvfile: list[str]) -> list[dict]", [](VM* vm, ArgsView args) {
        PyVar csv_reader = vm->_modules["csv"]->attr("reader");
        PyVar ret_obj = vm->call(csv_reader, args[0]);
        const List& ret = CAST(List&, ret_obj);
        if(ret.size() == 0) {
            vm->ValueError("empty csvfile");
        }
        const List& header = CAST(List&, ret[0]);
        List new_ret;
        for(int i = 1; i < ret.size(); i++) {
            const List& row = CAST(List&, ret[i]);
            if(row.size() != header.size()) {
                vm->ValueError("row.size() != header.size()");
            }
            Dict row_dict;
            for(int j = 0; j < header.size(); j++) {
                row_dict.set(vm, header[j], row[j]);
            }
            new_ret.push_back(VAR(std::move(row_dict)));
        }
        return VAR(std::move(new_ret));
    });
}

}  // namespace pkpy