#include <Python.h>

#include <errcode.h>

#include "pycore_pyerrors.h"      // _PyErr_ProgramDecodedTextObject()

#include "pycore_runtime.h"       // _Py_ID()

#include "pycore_tuple.h"         // _PyTuple_FromPair

#include "lexer/state.h"

#include "lexer/lexer.h"

#include "pegen.h"

// TOKENIZER ERRORS

static inline void

raise_unclosed_parentheses_error(Parser *p) {

       int error_lineno = p->tok->parenlinenostack[p->tok->level-1];

       int error_col = p->tok->parencolstack[p->tok->level-1];

       RAISE_ERROR_KNOWN_LOCATION(p, PyExc_SyntaxError,

                                  error_lineno, error_col, error_lineno, -1,

                                  "'%c' was never closed",

                                  p->tok->parenstack[p->tok->level-1]);

}

int

_Pypegen_tokenizer_error(Parser *p)

{

    if (PyErr_Occurred()) {

        return -1;

    }

    const char *msg = NULL;

    PyObject* errtype = PyExc_SyntaxError;

    Py_ssize_t col_offset = -1;

    p->error_indicator = 1;

    switch (p->tok->done) {

        case E_TOKEN:

            msg = "invalid token";

            break;

        case E_EOF:

            if (p->tok->level) {

                raise_unclosed_parentheses_error(p);

            } else {

                RAISE_SYNTAX_ERROR("unexpected EOF while parsing");

            }

            return -1;

        case E_DEDENT:

            RAISE_INDENTATION_ERROR("unindent does not match any outer indentation level");

            return -1;

        case E_INTR:

            if (!PyErr_Occurred()) {

                PyErr_SetNone(PyExc_KeyboardInterrupt);

            }

            return -1;

        case E_NOMEM:

            PyErr_NoMemory();

            return -1;

        case E_TABSPACE:

            errtype = PyExc_TabError;

            msg = "inconsistent use of tabs and spaces in indentation";

            break;

        case E_TOODEEP:

            errtype = PyExc_IndentationError;

            msg = "too many levels of indentation";

            break;

        case E_LINECONT: {

            col_offset = p->tok->cur - p->tok->buf - 1;

            msg = "unexpected character after line continuation character";

            break;

        }

        case E_COLUMNOVERFLOW:

            PyErr_SetString(PyExc_OverflowError,

                    "Parser column offset overflow - source line is too big");

            return -1;

        default:

            msg = "unknown parsing error";

    }

    RAISE_ERROR_KNOWN_LOCATION(p, errtype, p->tok->lineno,

                               col_offset >= 0 ? col_offset : 0,

                               p->tok->lineno, -1, msg);

    return -1;

}

int

_Pypegen_raise_decode_error(Parser *p)

{

    assert(PyErr_Occurred());

    const char *errtype = NULL;

    if (PyErr_ExceptionMatches(PyExc_UnicodeError)) {

        errtype = "unicode error";

    }

    else if (PyErr_ExceptionMatches(PyExc_ValueError)) {

        errtype = "value error";

    }

    if (errtype) {

        PyObject *type;

        PyObject *value;

        PyObject *tback;

        PyObject *errstr;

        PyErr_Fetch(&type, &value, &tback);

        errstr = PyObject_Str(value);

        if (errstr) {

            RAISE_SYNTAX_ERROR("(%s) %U", errtype, errstr);

            Py_DECREF(errstr);

        }

        else {

            PyErr_Clear();

            RAISE_SYNTAX_ERROR("(%s) unknown error", errtype);

        }

        Py_XDECREF(type);

        Py_XDECREF(value);

        Py_XDECREF(tback);

    }

    return -1;

}

static int

_PyPegen_tokenize_full_source_to_check_for_errors(Parser *p) {

    // Tokenize the whole input to see if there are any tokenization

    // errors such as mismatching parentheses. These will get priority

    // over generic syntax errors only if the line number of the error is

    // before the one that we had for the generic error.

    // We don't want to tokenize to the end for interactive input

    if (p->tok->prompt != NULL) {

        return 0;

    }

    PyObject *type, *value, *traceback;

    PyErr_Fetch(&type, &value, &traceback);

    Token *current_token = p->known_err_token != NULL ? p->known_err_token : p->tokens[p->fill - 1];

    Py_ssize_t current_err_line = current_token->lineno;

    int ret = 0;

    struct token new_token;

    _PyToken_Init(&new_token);

    for (;;) {

        switch (_PyTokenizer_Get(p->tok, &new_token)) {

            case ERRORTOKEN:

                if (PyErr_Occurred()) {

                    ret = -1;

                    goto exit;

                }

                if (p->tok->level != 0) {

                    int error_lineno = p->tok->parenlinenostack[p->tok->level-1];

                    if (current_err_line > error_lineno) {

                        raise_unclosed_parentheses_error(p);

                        ret = -1;

                        goto exit;

                    }

                }

                break;

            case ENDMARKER:

                break;

            default:

                continue;

        }

        break;

    }

exit:

    _PyToken_Free(&new_token);

    // If we're in an f-string, we want the syntax error in the expression part

    // to propagate, so that tokenizer errors (like expecting '}') that happen afterwards

    // do not swallow it.

    if (PyErr_Occurred() && p->tok->tok_mode_stack_index <= 0) {

        Py_XDECREF(value);

        Py_XDECREF(type);

        Py_XDECREF(traceback);

    } else {

        PyErr_Restore(type, value, traceback);

    }

    return ret;

}

// PARSER ERRORS

void *

_PyPegen_raise_error(Parser *p, PyObject *errtype, int use_mark, const char *errmsg, ...)

{

    // Bail out if we already have an error set.

    if (p->error_indicator && PyErr_Occurred()) {

        return NULL;

    }

    if (p->fill == 0) {

        va_list va;

        va_start(va, errmsg);

        _PyPegen_raise_error_known_location(p, errtype, 0, 0, 0, -1, errmsg, va);

        va_end(va);

        return NULL;

    }

    if (use_mark && p->mark == p->fill && _PyPegen_fill_token(p) < 0) {

        p->error_indicator = 1;

        return NULL;

    }

    Token *t = p->known_err_token != NULL

                   ? p->known_err_token

                   : p->tokens[use_mark ? p->mark : p->fill - 1];

    Py_ssize_t col_offset;

    Py_ssize_t end_col_offset = -1;

    if (t->col_offset == -1) {

        if (p->tok->cur == p->tok->buf) {

            col_offset = 0;

        } else {

            const char* start = p->tok->buf  ? p->tok->line_start : p->tok->buf;

            col_offset = Py_SAFE_DOWNCAST(p->tok->cur - start, intptr_t, int);

        }

    } else {

        col_offset = t->col_offset + 1;

    }

    if (t->end_col_offset != -1) {

        end_col_offset = t->end_col_offset + 1;

    }

    va_list va;

    va_start(va, errmsg);

    _PyPegen_raise_error_known_location(p, errtype, t->lineno, col_offset, t->end_lineno, end_col_offset, errmsg, va);

    va_end(va);

    return NULL;

}

static PyObject *

get_error_line_from_tokenizer_buffers(Parser *p, Py_ssize_t lineno)

{

    /* If the file descriptor is interactive, the source lines of the current

     * (multi-line) statement are stored in p->tok->interactive_src_start.

     * If not, we're parsing from a string, which means that the whole source

     * is stored in p->tok->str. */

    assert((p->tok->fp == NULL && p->tok->str != NULL) || p->tok->fp != NULL);

    char *cur_line = p->tok->fp_interactive ? p->tok->interactive_src_start : p->tok->str;

    if (cur_line == NULL) {

        assert(p->tok->fp_interactive);

        // We can reach this point if the tokenizer buffers for interactive source have not been

        // initialized because we failed to decode the original source with the given locale.

        return Py_GetConstant(Py_CONSTANT_EMPTY_STR);

    }

    Py_ssize_t relative_lineno = p->starting_lineno ? lineno - p->starting_lineno + 1 : lineno;

    const char* buf_end = p->tok->fp_interactive ? p->tok->interactive_src_end : p->tok->inp;

    if (buf_end < cur_line) {

        buf_end = cur_line + strlen(cur_line);

    }

    for (int i = 0; i < relative_lineno - 1; i++) {

        char *new_line = strchr(cur_line, '\n');

        // The assert is here for debug builds but the conditional that

        // follows is there so in release builds we do not crash at the cost

        // to report a potentially wrong line.

        assert(new_line != NULL && new_line + 1 < buf_end);

        if (new_line == NULL || new_line + 1 > buf_end) {

            break;

        }

        cur_line = new_line + 1;

    }

    char *next_newline;

    if ((next_newline = strchr(cur_line, '\n')) == NULL) { // This is the last line

        next_newline = cur_line + strlen(cur_line);

    }

    return PyUnicode_DecodeUTF8(cur_line, next_newline - cur_line, "replace");

}

void *

_PyPegen_raise_error_known_location(Parser *p, PyObject *errtype,

                                    Py_ssize_t lineno, Py_ssize_t col_offset,

                                    Py_ssize_t end_lineno, Py_ssize_t end_col_offset,

                                    const char *errmsg, va_list va)

{

    // Bail out if we already have an error set.

    if (p->error_indicator && PyErr_Occurred()) {

        return NULL;

    }

    PyObject *value = NULL;

    PyObject *errstr = NULL;

    PyObject *error_line = NULL;

    PyObject *tmp = NULL;

    p->error_indicator = 1;

    if (end_lineno == CURRENT_POS) {

        end_lineno = p->tok->lineno;

    }

    if (end_col_offset == CURRENT_POS) {

        end_col_offset = p->tok->cur - p->tok->line_start;

    }

    errstr = PyUnicode_FromFormatV(errmsg, va);

    if (!errstr) {

        goto error;

    }

    if (p->tok->fp_interactive && p->tok->interactive_src_start != NULL) {

        error_line = get_error_line_from_tokenizer_buffers(p, lineno);

    }

    else if (p->start_rule == Py_file_input) {

        error_line = _PyErr_ProgramDecodedTextObject(p->tok->filename,

                                                     (int) lineno, p->tok->encoding);

    }

    if (!error_line) {

        /* PyErr_ProgramTextObject was not called or returned NULL. If it was not called,

           then we need to find the error line from some other source, because

           p->start_rule != Py_file_input. If it returned NULL, then it either unexpectedly

           failed or we're parsing from a string or the REPL. There's a third edge case where

           we're actually parsing from a file, which has an E_EOF SyntaxError and in that case

           `PyErr_ProgramTextObject` fails because lineno points to last_file_line + 1, which

           does not physically exist */

        assert(p->tok->fp == NULL || p->tok->fp == stdin || p->tok->done == E_EOF);

        if (p->tok->lineno <= lineno && p->tok->inp > p->tok->buf) {

            Py_ssize_t size = p->tok->inp - p->tok->line_start;

            error_line = PyUnicode_DecodeUTF8(p->tok->line_start, size, "replace");

        }

        else if (p->tok->fp == NULL || p->tok->fp == stdin) {

            error_line = get_error_line_from_tokenizer_buffers(p, lineno);

        }

        else {

            error_line = Py_GetConstant(Py_CONSTANT_EMPTY_STR);

        }

        if (!error_line) {

            goto error;

        }

    }

    Py_ssize_t col_number = col_offset;

    Py_ssize_t end_col_number = end_col_offset;

    col_number = _PyPegen_byte_offset_to_character_offset(error_line, col_offset);

    if (col_number < 0) {

        goto error;

    }

    if (end_col_offset > 0) {

        end_col_number = _PyPegen_byte_offset_to_character_offset(error_line, end_col_offset);

        if (end_col_number < 0) {

            goto error;

        }

    }

    tmp = Py_BuildValue("(OnnNnn)", p->tok->filename, lineno, col_number, error_line, end_lineno, end_col_number);

    if (!tmp) {

        goto error;

    }

    value = _PyTuple_FromPair(errstr, tmp);

    Py_DECREF(tmp);

    if (!value) {

        goto error;

    }

    PyErr_SetObject(errtype, value);

    Py_DECREF(errstr);

    Py_DECREF(value);

    return NULL;

error:

    Py_XDECREF(errstr);

    Py_XDECREF(error_line);

    return NULL;

}

void

_Pypegen_set_syntax_error(Parser* p, Token* last_token) {

    // Existing syntax error

    if (PyErr_Occurred()) {

        // Prioritize tokenizer errors to custom syntax errors raised

        // on the second phase only if the errors come from the parser.

        int is_tok_ok = (p->tok->done == E_DONE || p->tok->done == E_OK);

        if (is_tok_ok && PyErr_ExceptionMatches(PyExc_SyntaxError)) {

            _PyPegen_tokenize_full_source_to_check_for_errors(p);

        }

        // Propagate the existing syntax error.

        return;

    }

    // Initialization error

    if (p->fill == 0) {

        RAISE_SYNTAX_ERROR("error at start before reading any input");

    }

    // Parser encountered EOF (End of File) unexpectedtly

    if (last_token->type == ERRORTOKEN && p->tok->done == E_EOF) {

        if (p->tok->level) {

            raise_unclosed_parentheses_error(p);

        } else {

            RAISE_SYNTAX_ERROR("unexpected EOF while parsing");

        }

        return;

    }

    // Indentation error in the tokenizer

    if (last_token->type == INDENT || last_token->type == DEDENT) {

        RAISE_INDENTATION_ERROR(last_token->type == INDENT ? "unexpected indent" : "unexpected unindent");

        return;

    }

    // Unknown error (generic case)

    // Use the last token we found on the first pass to avoid reporting

    // incorrect locations for generic syntax errors just because we reached

    // further away when trying to find specific syntax errors in the second

    // pass.

    RAISE_SYNTAX_ERROR_KNOWN_LOCATION(last_token, "invalid syntax");

    // _PyPegen_tokenize_full_source_to_check_for_errors will override the existing

    // generic SyntaxError we just raised if errors are found.

    _PyPegen_tokenize_full_source_to_check_for_errors(p);

}

void

_Pypegen_stack_overflow(Parser *p)

{

    p->error_indicator = 1;

    PyErr_SetString(PyExc_MemoryError,

        "Parser stack overflowed - Python source too complex to parse");

}