/*
 * Hurl (https://hurl.dev)
 * Copyright (C) 2026 Orange
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *          http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
use std::ffi::{CStr, CString};
use std::os::raw::c_char;
use std::ptr;

use libxml::bindings::{htmlReadMemory, xmlReadMemory};
use libxml::parser::{ParseFormat, Parser, XmlParseError};

use super::number::Number;
use super::value::Value;

/// An error for XPath evaluation.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum XPathError {
    Eval,
    Unsupported,
}

/// A structure to hold a libxml document tree.
#[derive(Clone)]
pub struct Document {
    /// The inner libxml document
    inner: libxml::tree::Document,
    /// Format use for parsing: HTML or XML
    format: Format,
}

#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum Format {
    Html,
    Xml,
}

impl Document {
    /// Parses a XML/HTML string data.
    pub fn parse(data: &str, format: Format) -> Result<Document, String> {
        let parser = match format {
            Format::Html => Parser::default_html(),
            Format::Xml => Parser::default(),
        };

        let Ok(doc) = parse_html_string_patched(data, &parser) else {
            return Err("invalid input data".to_string());
        };

        // You can have a doc structure even if the input xml is not valid, we check that the root
        // element exists
        if doc.get_root_element().is_none() {
            return Err("no root element".to_string());
        }

        let doc = Document { inner: doc, format };
        Ok(doc)
    }

    /// Evaluates a XPath 1.0 expression `expr` against a document.
    pub fn eval_xpath(&self, expr: &str) -> Result<Value, XPathError> {
        let support_ns = match self.format {
            Format::Html => false,
            Format::Xml => true,
        };
        libxml_eval_xpath(&self.inner, expr, support_ns)
    }
}

/// FIXME: Here are some patched functions of libxml crate.
/// Started from libxml 2.11.1+, we have some encoding issue.
/// See:
/// - <https://github.com/KWARC/rust-libxml/issues/111>
/// - <https://github.com/Orange-OpenSource/hurl/issues/1535>
///
/// These two functions should be removed when the issue is fixed in libxml crate.
fn try_usize_to_i32(value: usize) -> Result<i32, XmlParseError> {
    if cfg!(target_pointer_width = "16") || (value < i32::MAX as usize) {
        // Cannot safely use our value comparison, but the conversion if always safe.
        // Or, if the value can be safely represented as a 32-bit signed integer.
        Ok(value as i32)
    } else {
        // Document too large, cannot parse using libxml2.
        Err(XmlParseError::DocumentTooLarge)
    }
}

fn parse_html_string_patched(
    input: &str,
    parser: &Parser,
) -> Result<libxml::tree::Document, XmlParseError> {
    let input_bytes: &[u8] = input.as_ref();
    let input_ptr = input_bytes.as_ptr() as *const c_char;
    let input_len = try_usize_to_i32(input_bytes.len())?;
    let encoding = CString::new("utf-8").unwrap();
    let encoding_ptr = encoding.as_ptr();
    let url_ptr = ptr::null();

    // HTML_PARSE_RECOVER | HTML_PARSE_NOERROR
    let options = 1 + 32;
    match parser.format {
        ParseFormat::XML => unsafe {
            let doc_ptr = xmlReadMemory(input_ptr, input_len, url_ptr, encoding_ptr, options);
            if doc_ptr.is_null() {
                Err(XmlParseError::GotNullPointer)
            } else {
                Ok(libxml::tree::Document::new_ptr(doc_ptr))
            }
        },
        ParseFormat::HTML => unsafe {
            let docptr = htmlReadMemory(input_ptr, input_len, url_ptr, encoding_ptr, options);
            if docptr.is_null() {
                Err(XmlParseError::GotNullPointer)
            } else {
                Ok(libxml::tree::Document::new_ptr(docptr))
            }
        },
    }
}

unsafe extern "C" {
    pub fn silentErrorFunc(
        ctx: *mut ::std::os::raw::c_void,
        msg: *const ::std::os::raw::c_char,
        ...
    );
}

/// Registers all XML namespaces from a document `doc` to a `context`.
fn register_namespaces(doc: &libxml::tree::Document, context: &libxml::xpath::Context) {
    // We walk through the xml document to register each namespace,
    // so we can eval xpath queries with namespace. For convenience, we register the
    // first default namespace with _ prefix. Other default namespaces are not registered
    // and should be referenced vi `local-name` or `name` XPath functions.
    let namespaces = document_namespaces(doc);
    let mut default_registered = false;

    for n in namespaces {
        if n.prefix.is_empty() {
            if !default_registered {
                context.register_namespace("_", &n.href).unwrap();
                default_registered = true;
            }
        } else {
            context.register_namespace(&n.prefix, &n.href).unwrap();
        }
    }
}

/// Evaluates a XPath 1.0 expression `expr` against an libxml2 document `doc`, optionally using namespace.
fn libxml_eval_xpath(
    doc: &libxml::tree::Document,
    expr: &str,
    support_ns: bool,
) -> Result<Value, XPathError> {
    let context = libxml::xpath::Context::new(doc).expect("error setting context in xpath module");

    // libxml2 prints to stdout warning and errors, so we mut it.
    unsafe {
        libxml::bindings::xmlSetGenericErrorFunc(ptr::null_mut(), Some(silentErrorFunc));
    }

    if support_ns {
        register_namespaces(doc, &context);
    }

    let result = match context.evaluate(expr) {
        Ok(object) => object,
        Err(_) => return Err(XPathError::Eval),
    };

    match unsafe { *result.ptr }.type_ {
        libxml::bindings::xmlXPathObjectType_XPATH_NUMBER => {
            Ok(Value::Number(Number::from(unsafe { *result.ptr }.floatval)))
        }
        libxml::bindings::xmlXPathObjectType_XPATH_BOOLEAN => {
            Ok(Value::Bool(unsafe { *result.ptr }.boolval != 0))
        }
        libxml::bindings::xmlXPathObjectType_XPATH_STRING => {
            // TO BE CLEANED
            let c_s = unsafe { *result.ptr }.stringval;
            let c_s2 = c_s as *const c_char;
            let x = unsafe { CStr::from_ptr(c_s2) };
            let s = x.to_string_lossy().to_string();

            Ok(Value::String(s))
        }
        libxml::bindings::xmlXPathObjectType_XPATH_NODESET => {
            Ok(Value::Nodeset(result.get_number_of_nodes()))
        }
        _ => Err(XPathError::Unsupported),
    }
}

/// A XML namespace
#[derive(Debug, PartialEq, Eq)]
struct Namespace {
    prefix: String,
    href: String,
}

impl Namespace {
    /// Create a Namespace given a libxml2 namespace reference.
    fn from(namespace: &libxml::tree::Namespace) -> Namespace {
        Namespace {
            prefix: namespace.get_prefix(),
            href: namespace.get_href(),
        }
    }
}

/// Returns all XML namespaces for a libxml2 document.
fn document_namespaces(doc: &libxml::tree::Document) -> Vec<Namespace> {
    let root = doc.get_root_element();
    let root = match root {
        None => return vec![],
        Some(r) => r,
    };
    namespaces(&root)
}

/// Returns all XML namespaces for a given libxml2 node.
fn namespaces(node: &libxml::tree::Node) -> Vec<Namespace> {
    let mut all_ns = Vec::new();

    // Get namespaces from the current node
    let ns: Vec<Namespace> = node
        .get_namespace_declarations()
        .into_iter()
        .map(|n| Namespace::from(&n))
        .collect();
    all_ns.extend(ns);

    // Get children namespaces
    let ns: Vec<Namespace> = node
        .get_child_nodes()
        .into_iter()
        .flat_map(|c| namespaces(&c))
        .collect();
    all_ns.extend(ns);

    all_ns
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_xml() {
        let xml = r#"<?xml version="1.0" encoding="utf-8"?>
<food>
  <banana type="fruit" price="1.1"/>
  <apple type="fruit"/>
  <beef type="meat"/>
</food>
"#;
        let doc = Document::parse(xml, Format::Xml).unwrap();

        let xpath = "count(//food/*)";
        assert_eq!(
            doc.eval_xpath(xpath).unwrap(),
            Value::Number(Number::from(3.0))
        );

        let xpath = "//food/*";
        assert_eq!(doc.eval_xpath(xpath).unwrap(), Value::Nodeset(3));

        let xpath = "count(//*[@type='fruit'])";
        assert_eq!(
            doc.eval_xpath(xpath).unwrap(),
            Value::Number(Number::from(2.0))
        );

        let xpath = "number(//food/banana/@price)";
        assert_eq!(
            doc.eval_xpath(xpath).unwrap(),
            Value::Number(Number::from(1.1))
        );
    }

    #[test]
    fn test_error_eval() {
        let xml = "<a/>";
        let doc = Document::parse(xml, Format::Xml).unwrap();

        assert_eq!(doc.eval_xpath("^^^").unwrap_err(), XPathError::Eval);
        assert_eq!(doc.eval_xpath("//").unwrap_err(), XPathError::Eval);
        // assert_eq!(1,2);
    }

    // TBC!!!
    // Invalid XML not detected at parsing??? => goes into an eval error
    #[test]
    fn test_invalid_xml() {
        let xml = "??";
        let doc = Document::parse(xml, Format::Xml);
        assert!(doc.is_err());
    }

    #[test]
    fn test_cafe_xml() {
        let xml = "<data>café</data>";
        let doc = Document::parse(xml, Format::Xml).unwrap();

        assert_eq!(
            doc.eval_xpath("normalize-space(//data)").unwrap(),
            Value::String(String::from("café"))
        );
    }

    #[test]
    fn test_cafe_html() {
        let html = "<data>café</data>";
        let doc = Document::parse(html, Format::Html).unwrap();

        assert_eq!(
            doc.eval_xpath("normalize-space(//data)").unwrap(),
            Value::String(String::from("café"))
        );
    }

    #[test]
    fn test_html() {
        let html = r#"<html>
  <head>
    <meta charset="UTF-8"\>
  </head>
  <body>
    <br>
  </body>
</html>"#;
        let doc = Document::parse(html, Format::Html).unwrap();
        let xpath = "normalize-space(/html/head/meta/@charset)";
        assert_eq!(
            doc.eval_xpath(xpath).unwrap(),
            Value::String(String::from("UTF-8"))
        );
    }

    #[test]
    fn test_bug() {
        let html = r#"<html></html>"#;
        let doc = Document::parse(html, Format::Html).unwrap();
        let xpath = "boolean(count(//a[contains(@href,'xxx')]))";
        assert_eq!(doc.eval_xpath(xpath).unwrap(), Value::Bool(false));
    }

    #[test]
    fn test_unregistered_function() {
        let html = r#"<html></html>"#;
        let doc = Document::parse(html, Format::Html).unwrap();
        let xpath = "strong(//head/title)";
        assert_eq!(doc.eval_xpath(xpath).unwrap_err(), XPathError::Eval);
    }

    #[test]
    fn test_namespaces_with_prefix() {
        let xml = r#"<?xml version ="1.0"?>
<a:books xmlns:a="foo:" xmlns:b="bar:">
    <b:book xmlns:c="baz:">
        <b:title>Dune</b:title>
        <c:author>Franck Herbert</c:author>
    </b:book>
</a:books>"#;

        let doc = Document::parse(xml, Format::Xml).unwrap();

        let expr = "string(//a:books/b:book/b:title)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("Dune".to_string())
        );

        let expr = "string(//a:books/b:book/c:author)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("Franck Herbert".to_string())
        );

        let expr = "string(//*[name()='a:books']/*[name()='b:book']/*[name()='c:author'])";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("Franck Herbert".to_string())
        );

        let expr =
            "string(//*[local-name()='books']/*[local-name()='book']/*[local-name()='author'])";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("Franck Herbert".to_string())
        );
    }

    #[test]
    fn test_default_namespaces() {
        let xml = r#"<svg version="1.1" width="300" height="200" xmlns="http://www.w3.org/2000/svg">
    <rect width="100%" height="100%" fill="red" />
    <circle cx="150" cy="100" r="80" fill="green" />
    <text x="150" y="125" font-size="60" text-anchor="middle" fill="white">SVG</text>
</svg>"#;
        let doc = Document::parse(xml, Format::Xml).unwrap();

        let expr = "string(//_:svg/_:text)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("SVG".to_string())
        );

        let expr = "string(//*[name()='svg']/*[name()='text'])";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("SVG".to_string())
        );

        let expr = "string(//*[local-name()='svg']/*[local-name()='text'])";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("SVG".to_string())
        );
    }

    #[test]
    fn test_soap() {
        let xml = r#"<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <soap:Body xmlns:ns1="http://www.opentravel.org/OTA/2003/05">
        <ns1:OTA_AirAvailRS
            EchoToken="11868765275150-1300257934"
            PrimaryLangID="en-us"
            RetransmissionIndicator="false"
            SequenceNmbr="1"
            TransactionIdentifier="TID$16459590516432752971.demo2144"
            Version="2006.01">
        </ns1:OTA_AirAvailRS>
    </soap:Body>
</soap:Envelope>"#;

        let doc = Document::parse(xml, Format::Xml).unwrap();

        let expr = "string(//soap:Envelope/soap:Body/ns1:OTA_AirAvailRS/@TransactionIdentifier)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("TID$16459590516432752971.demo2144".to_string())
        );

        let expr = "string(//*[name()='soap:Envelope']/*[name()='soap:Body']/*[name()='ns1:OTA_AirAvailRS']/@TransactionIdentifier)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("TID$16459590516432752971.demo2144".to_string())
        );

        let expr = "string(//*[local-name()='Envelope']/*[local-name()='Body']/*[local-name()='OTA_AirAvailRS']/@TransactionIdentifier)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("TID$16459590516432752971.demo2144".to_string())
        );
    }

    #[test]
    fn test_namespaces_scoping() {
        let xml = r#"<?xml version="1.0"?>
<!-- initially, the default namespace is "books" -->
<book xmlns='urn:loc.gov:books'
      xmlns:isbn='urn:ISBN:0-395-36341-6'>
    <title>Cheaper by the Dozen</title>
    <isbn:number>1568491379</isbn:number>
    <notes>
      <!-- make HTML the default namespace for some commentary -->
      <p xmlns='http://www.w3.org/1999/xhtml'>
          This is a <i>funny</i> book!
      </p>
    </notes>
</book>
        "#;

        let doc = Document::parse(xml, Format::Xml).unwrap();

        let expr = "string(//_:book/_:title)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("Cheaper by the Dozen".to_string())
        );

        let expr = "string(//_:book/isbn:number)";
        assert_eq!(
            doc.eval_xpath(expr).unwrap(),
            Value::String("1568491379".to_string())
        );

        let expr = "//*[name()='book']/*[name()='notes']";
        assert_eq!(doc.eval_xpath(expr).unwrap(), Value::Nodeset(1));

        let expr = "//_:book/_:notes/*[local-name()='p']";
        assert_eq!(doc.eval_xpath(expr).unwrap(), Value::Nodeset(1));
    }
}
