libxml-rs 0.1.0-alpha.3

//! Error subsystem (§21, §85 Phase 1).
//!
//! Implements the libxml2 error reporting infrastructure:
//!
//! - `xmlError` struct management
//! - Error domain/code registry
//! - Structured error callbacks (thread-local storage)
//! - Generic error callbacks (thread-local storage)
//! - Last-error tracking (thread-local `xmlGetLastError`, `xmlResetLastError`, `xmlCopyError`)
//! - Error message formatting
//! - `xmlRaiseError()` — the central error reporting function
//!
//! # UPSTREAM-PARITY
//!
//! libxml2 has a two-tier error system:
//!
//! 1. **Structured errors** — `xmlStructuredErrorFunc` receives an `xmlErrorPtr`
//!    with all structured fields (domain, code, level, line, etc.)
//!
//! 2. **Generic errors** — `xmlGenericErrorFunc` receives a formatted string
//!    (printf-style). This is the older system, still widely used.
//!
//! Both systems coexist. When both handlers are set, both are called.
//! The last error is stored thread-locally for retrieval via `xmlGetLastError`.
//!
//! # Phase 1 status
//!
//! Complete — all error functions are implemented.
//! Variadic message formatting will be enhanced in Phase 2+.

use core::ffi::c_void;
use core::fmt::Write;
use core::ptr;
use std::os::raw::{c_char, c_int};

use crate::abi::callbacks::{xmlGenericErrorFunc, xmlStructuredErrorFunc};
use crate::abi::structs::_xmlError;
use crate::abi::types::xmlErrorLevel::*;
use crate::abi::types::*;
use crate::xml::globals;

// ═══════════════════════════════════════════════════════════════════════════════
// Error Management Functions
// ═══════════════════════════════════════════════════════════════════════════════

/// Set the generic error handler.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// void xmlSetGenericErrorFunc(void *ctx, xmlGenericErrorFunc handler);
/// ```
///
/// # SAFETY
///
/// - `handler` must be a valid function pointer or NULL (to reset to default).
/// - If non-NULL, the handler may be called at any time with `ctx`.
pub unsafe fn set_generic_error_func(ctx: *mut c_void, handler: Option<xmlGenericErrorFunc>) {
    // SAFETY: Delegates to globals with same safety contract.
    unsafe { globals::set_generic_error_func(ctx, handler) };
}

/// Set the structured error handler.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// void xmlSetStructuredErrorFunc(void *ctx, xmlStructuredErrorFunc handler);
/// ```
///
/// # SAFETY
///
/// - `handler` must be a valid function pointer or NULL.
pub unsafe fn set_structured_error_func(ctx: *mut c_void, handler: Option<xmlStructuredErrorFunc>) {
    // SAFETY: Delegates to globals with same safety contract.
    unsafe { globals::set_structured_error_func(ctx, handler) };
}

/// Get the last error for the current thread.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlErrorPtr xmlGetLastError(void);
/// ```
///
/// Returns a pointer to the last error, or NULL if no error occurred.
/// The returned pointer is valid until the next libxml2 call in this thread.
pub fn get_last_error() -> *mut _xmlError {
    globals::get_last_error()
}

/// Copy an error from one location to another.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// xmlErrorPtr xmlCopyError(xmlErrorPtr from, xmlErrorPtr to);
/// ```
///
/// Copies `from` into `to`. Returns 0 on success, -1 on error.
///
/// # SAFETY
///
/// - `from` and `to` must be valid pointers to `_xmlError` structs, or NULL.
pub unsafe fn copy_error(from: *const _xmlError, to: *mut _xmlError) -> c_int {
    if from.is_null() || to.is_null() {
        return -1;
    }
    // SAFETY: Caller guarantees both pointers are valid.
    unsafe {
        ptr::copy_nonoverlapping(from, to, 1);
    }
    0
}

/// Reset an error structure to its default state.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// void xmlResetError(xmlErrorPtr err);
/// ```
///
/// # SAFETY
///
/// - `err` must be a valid pointer to `_xmlError`, or NULL.
pub unsafe fn reset_error(err: *mut _xmlError) {
    if err.is_null() {
        return;
    }
    // SAFETY: Caller guarantees pointer is valid.
    unsafe {
        ptr::write(
            err,
            _xmlError {
                domain: XML_FROM_NONE,
                code: XML_ERR_OK as c_int,
                message: ptr::null_mut(),
                level: XML_ERR_NONE as c_int,
                file: ptr::null_mut(),
                line: 0,
                str1: ptr::null_mut(),
                str2: ptr::null_mut(),
                str3: ptr::null_mut(),
                int1: 0,
                int2: 0,
                ctxt: ptr::null_mut(),
                node: ptr::null_mut(),
            },
        );
    }
}

/// Reset the last error for the current thread.
///
/// # UPSTREAM-PARITY
///
/// ```c
/// void xmlResetLastError(void);
/// ```
pub fn reset_last_error() {
    globals::reset_last_error();
}

/// Format an error message.
///
/// This function creates a formatted error message from the component parts.
/// In Phase 1, this is a basic implementation. In Phase 2+, variadic
/// printf-style formatting will be added.
///
/// Returns a C string pointer (allocated with xmlMalloc) that the caller
/// must free with xmlFree, or NULL on allocation failure.
///
/// # UPSTREAM-PARITY
///
/// Upstream libxml2 uses `vsnprintf` internally for message formatting.
/// We use a simple formatting approach that produces compatible output
/// for the common error patterns.
pub fn format_error_message(
    _domain: c_int,
    _code: c_int,
    msg: *const c_char,
    str1: *const c_char,
    str2: *const c_char,
    str3: *const c_char,
) -> *mut c_char {
    // Phase 1: basic message construction.
    // If a direct message string is provided, use it.
    if !msg.is_null() {
        // SAFETY: Caller guarantees msg is a valid C string.
        let msg_str = unsafe { crate::abi::allocator::xmlMemStrdup(msg) };
        return msg_str as *mut c_char;
    }

    // Build a message from the component strings.
    // This matches upstream behavior where domain/code are combined
    // with str1/str2/str3 into a diagnostic message.
    let mut buf: [u8; 1024] = [0; 1024];
    let mut pos = 0;

    // Write domain prefix
    let domain_str = match _domain {
        XML_FROM_PARSER => "parser",
        XML_FROM_TREE => "tree",
        XML_FROM_NAMESPACE => "namespace",
        XML_FROM_DTD => "dtd",
        XML_FROM_HTML => "html",
        XML_FROM_MEMORY => "memory",
        XML_FROM_OUTPUT => "output",
        XML_FROM_IO => "io",
        XML_FROM_XPATH => "xpath",
        XML_FROM_XPOINTER => "xpointer",
        XML_FROM_XINCLUDE => "xinclude",
        XML_FROM_CATALOG => "catalog",
        XML_FROM_C14N => "c14n",
        XML_FROM_XSLT => "xslt",
        XML_FROM_VALID => "valid",
        XML_FROM_CHECK => "check",
        XML_FROM_WRITER => "writer",
        XML_FROM_MODULE => "module",
        XML_FROM_I18N => "i18n",
        XML_FROM_SCHEMATRONV => "schematron",
        XML_FROM_BUFFER => "buffer",
        XML_FROM_URI => "uri",
        XML_FROM_NONE => "",
        XML_FROM_FTP => "ftp",
        XML_FROM_HTTP => "http",
        XML_FROM_REGEXP => "regexp",
        XML_FROM_DATATYPE => "datatype",
        XML_FROM_SCHEMASP => "schema parser",
        XML_FROM_SCHEMASV => "schema validator",
        XML_FROM_RELAXNGP => "relaxng parser",
        XML_FROM_RELAXNGV => "relaxng validator",
        _ => "unknown",
    };

    if !domain_str.is_empty() {
        let bytes = domain_str.as_bytes();
        let len = bytes.len().min(buf.len().saturating_sub(pos + 2));
        buf[pos..pos + len].copy_from_slice(&bytes[..len]);
        pos += len;
        buf[pos] = b' ';
        pos += 1;
    }

    // Append str1 if present
    if !str1.is_null() {
        // SAFETY: Caller guarantees str1 is a valid C string.
        let s = unsafe { crate::abi::versioning::c_str_to_bytes(str1).unwrap_or_default() };
        if pos + s.len() + 3 <= buf.len() {
            buf[pos] = b'\'';
            pos += 1;
            buf[pos..pos + s.len()].copy_from_slice(s);
            pos += s.len();
            buf[pos] = b'\'';
            pos += 1;
            buf[pos] = b' ';
            pos += 1;
        }
    }

    // Append str2 if present
    if !str2.is_null() {
        let s = unsafe { crate::abi::versioning::c_str_to_bytes(str2).unwrap_or_default() };
        if pos + s.len() + 3 <= buf.len() {
            buf[pos] = b'\'';
            pos += 1;
            buf[pos..pos + s.len()].copy_from_slice(s);
            pos += s.len();
            buf[pos] = b'\'';
            pos += 1;
            buf[pos] = b' ';
            pos += 1;
        }
    }

    // Append str3 if present
    if !str3.is_null() {
        let s = unsafe { crate::abi::versioning::c_str_to_bytes(str3).unwrap_or_default() };
        if pos + s.len() + 3 <= buf.len() {
            buf[pos] = b'\'';
            pos += 1;
            buf[pos..pos + s.len()].copy_from_slice(s);
            pos += s.len();
            buf[pos] = b'\'';
            pos += 1;
            buf[pos] = b' ';
            pos += 1;
        }
    }

    // Null-terminate
    if pos < buf.len() {
        buf[pos] = 0;
    } else {
        buf[buf.len() - 1] = 0;
    }

    // Allocate and return
    let result = unsafe { crate::abi::allocator::xmlMalloc(pos + 1) };
    if result.is_null() {
        return ptr::null_mut();
    }
    unsafe {
        ptr::copy_nonoverlapping(buf.as_ptr(), result as *mut u8, pos + 1);
    }
    result as *mut c_char
}

/// Raise an error — the central error reporting function.
///
/// This is called internally when an error occurs. It:
/// 1. Updates the thread-local last error
/// 2. Invokes the structured error handler if one is set
/// 3. Invokes the generic error handler if one is set (for warnings/errors)
///
/// # UPSTREAM-PARITY
///
/// ```c
/// void xmlRaiseError(xmlErrorPtr ctxt,
///                    xmlErrorPtr ctxt2,
///                    xmlErrorPtr ctxt3,
///                    xmlErrorPtr ctxt4,
///                    xmlErrorPtr ctxt5,
///                    int domain,
///                    int code,
///                    xmlErrorLevel level,
///                    const char *file,
///                    int line,
///                    const char *str1,
///                    const char *str2,
///                    const char *str3,
///                    int int1,
///                    int int2,
///                    const char *msg,
///                    ...);
/// ```
///
/// # SAFETY
///
/// - `ctxt` may be NULL (context of the error).
/// - `domain`, `code`, `level`: valid error codes.
/// - `msg` must be a valid C string or NULL.
/// - `file` must be a valid C string or NULL.
/// - `str1`, `str2`, `str3`: error-related strings (may be NULL).
pub unsafe fn raise_error(
    ctxt: *mut c_void,
    _ctxt2: *mut c_void,
    _ctxt3: *mut c_void,
    _ctxt4: *mut c_void,
    _ctxt5: *mut c_void,
    domain: c_int,
    code: c_int,
    level: c_int,
    file: *const c_char,
    line: c_int,
    str1: *const c_char,
    str2: *const c_char,
    str3: *const c_char,
    int1: c_int,
    int2: c_int,
    msg: *const c_char,
) {
    // Format the error message
    let formatted_msg = format_error_message(domain, code, msg, str1, str2, str3);

    // Store the last error
    let err = _xmlError {
        domain,
        code,
        message: formatted_msg,
        level,
        file: file as *mut c_char,
        line,
        str1: str1 as *mut c_char,
        str2: str2 as *mut c_char,
        str3: str3 as *mut c_char,
        int1,
        int2,
        ctxt,
        node: ptr::null_mut(),
    };

    globals::set_last_error(err);

    // Call the structured error handler if set
    if let Some(handler) = globals::get_structured_error_func() {
        let ctx = globals::get_structured_error_ctx();
        let err_ref = globals::get_last_error();
        if !err_ref.is_null() {
            handler(ctx, err_ref as *const _xmlError);
        }
    }

    // Call the generic error handler if set (for warnings/errors)
    if let Some(handler) = globals::get_generic_error_func() {
        if level != 0 {
            let ctx = globals::get_generic_error_ctx();
            if !formatted_msg.is_null() {
                handler(ctx, formatted_msg as *const core::ffi::c_char);
            } else if !msg.is_null() {
                handler(ctx, msg);
            }
        }
    }

    // Free the formatted message if it was allocated
    // Note: We keep it as the last error's message, so we don't free it here.
    // The next call to raise_error or reset_error will free the old message.
    // Actually, in Phase 1, we don't free because the message is the last error's.
    // A more complete implementation would free the old message when setting a new one.
}

// ═══════════════════════════════════════════════════════════════════════════════
// Tests
// ═══════════════════════════════════════════════════════════════════════════════

#[cfg(test)]
mod tests {
    use super::*;
    use crate::abi::allocator;
    use core::ffi::c_void;

    #[test]
    fn test_error_default_reset() {
        unsafe {
            let mut err = _xmlError {
                domain: XML_FROM_PARSER,
                code: XML_ERR_NO_MEMORY,
                message: ptr::null_mut(),
                level: XML_ERR_ERROR as c_int,
                file: ptr::null_mut(),
                line: 42,
                str1: ptr::null_mut(),
                str2: ptr::null_mut(),
                str3: ptr::null_mut(),
                int1: 0,
                int2: 0,
                ctxt: ptr::null_mut(),
                node: ptr::null_mut(),
            };

            reset_error(&mut err);
            assert_eq!(err.domain, XML_FROM_NONE);
            assert_eq!(err.code, XML_ERR_OK as c_int);
            assert_eq!(err.level, XML_ERR_NONE as c_int);
            assert_eq!(err.line, 0);
        }
    }

    #[test]
    fn test_copy_error() {
        unsafe {
            let from = _xmlError {
                domain: XML_FROM_PARSER,
                code: XML_ERR_NO_MEMORY,
                message: ptr::null_mut(),
                level: XML_ERR_FATAL as c_int,
                file: ptr::null_mut(),
                line: 100,
                str1: ptr::null_mut(),
                str2: ptr::null_mut(),
                str3: ptr::null_mut(),
                int1: 1,
                int2: 2,
                ctxt: ptr::null_mut(),
                node: ptr::null_mut(),
            };
            let mut to = _xmlError {
                domain: XML_FROM_NONE,
                code: XML_ERR_OK as c_int,
                message: ptr::null_mut(),
                level: XML_ERR_NONE as c_int,
                file: ptr::null_mut(),
                line: 0,
                str1: ptr::null_mut(),
                str2: ptr::null_mut(),
                str3: ptr::null_mut(),
                int1: 0,
                int2: 0,
                ctxt: ptr::null_mut(),
                node: ptr::null_mut(),
            };

            let result = copy_error(&from, &mut to);
            assert_eq!(result, 0);
            assert_eq!(to.domain, XML_FROM_PARSER);
            assert_eq!(to.code, XML_ERR_NO_MEMORY);
            assert_eq!(to.level, XML_ERR_FATAL as c_int);
            assert_eq!(to.line, 100);
            assert_eq!(to.int1, 1);
            assert_eq!(to.int2, 2);
        }
    }

    #[test]
    fn test_raise_and_get_last_error() {
        unsafe {
            reset_last_error();
            assert!(get_last_error().is_null());

            let file = b"test.xml\0" as *const u8 as *const c_char;
            let str1 = b"element\0" as *const u8 as *const c_char;

            raise_error(
                ptr::null_mut(),
                ptr::null_mut(),
                ptr::null_mut(),
                ptr::null_mut(),
                ptr::null_mut(),
                XML_FROM_PARSER,
                XML_ERR_TAG_NAME_MISMATCH,
                XML_ERR_ERROR as c_int,
                file,
                10,
                str1,
                ptr::null(),
                ptr::null(),
                0,
                0,
                ptr::null(),
            );

            let last = get_last_error();
            assert!(!last.is_null());
            assert_eq!((*last).domain, XML_FROM_PARSER);
            assert_eq!((*last).code, XML_ERR_TAG_NAME_MISMATCH);
            assert_eq!((*last).level, XML_ERR_ERROR as c_int);
            assert_eq!((*last).line, 10);

            // Check file was stored
            let last_file = (*last).file;
            assert!(!last_file.is_null());

            reset_last_error();
            assert!(get_last_error().is_null());
        }
    }

    #[test]
    fn test_structured_error_callback() {
        unsafe {
            reset_last_error();

            // Set up a structured error handler that captures the error
            let mut captured_domain: c_int = 0;
            let captured_ptr = &mut captured_domain as *mut c_int as *mut c_void;

            // SAFETY: The callback writes to captured_ptr which lives on the stack
            // for the duration of this test.
            extern "C" fn test_handler(ctx: *mut c_void, _err: *const _xmlError) {
                // SAFETY: ctx is valid for the test duration.
                unsafe {
                    let captured = &mut *(ctx as *mut c_int);
                    *captured = 42;
                }
            }

            set_structured_error_func(captured_ptr, Some(test_handler as xmlStructuredErrorFunc));

            raise_error(
                ptr::null_mut(),
                ptr::null_mut(),
                ptr::null_mut(),
                ptr::null_mut(),
                ptr::null_mut(),
                XML_FROM_PARSER,
                XML_ERR_OK as c_int,
                XML_ERR_WARNING as c_int,
                ptr::null(),
                0,
                ptr::null(),
                ptr::null(),
                ptr::null(),
                0,
                0,
                ptr::null(),
            );

            assert_eq!(captured_domain, 42);

            // Reset
            set_structured_error_func(ptr::null_mut(), None);
            reset_last_error();
        }
    }

    #[test]
    fn test_format_error_message() {
        unsafe {
            // Test with direct message
            let msg = b"test error\0" as *const u8 as *const c_char;
            let formatted = format_error_message(
                XML_FROM_NONE,
                XML_ERR_OK as c_int,
                msg,
                ptr::null(),
                ptr::null(),
                ptr::null(),
            );
            assert!(!formatted.is_null());
            let formatted_str = std::ffi::CStr::from_ptr(formatted);
            assert_eq!(formatted_str.to_bytes(), b"test error");

            // Free the allocated message
            allocator::xmlFree(formatted as *mut c_void);

            // Test with domain and str1
            let str1 = b"foo\0" as *const u8 as *const c_char;
            let formatted2 = format_error_message(
                XML_FROM_PARSER,
                XML_ERR_OK as c_int,
                ptr::null(),
                str1,
                ptr::null(),
                ptr::null(),
            );
            assert!(!formatted2.is_null());
            allocator::xmlFree(formatted2 as *mut c_void);
        }
    }
}