use crate::files::load_to_graph;
use crate::vocab::*;
use anyhow::{anyhow, Result};
use oxigraph::model::vocab::*;
use oxigraph::model::*;
use std::collections::VecDeque;
use std::fmt;

pub struct Test {
    pub id: NamedNode,
    pub kind: NamedNode,
    pub name: Option<String>,
    pub comment: Option<String>,
    pub action: Option<String>,
    pub query: Option<String>,
    pub update: Option<String>,
    pub data: Option<String>,
    pub graph_data: Vec<(NamedNode, String)>,
    pub service_data: Vec<(String, String)>,
    pub result: Option<String>,
    pub result_graph_data: Vec<(NamedNode, String)>,
}

impl fmt::Display for Test {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", self.kind)?;
        for name in &self.name {
            write!(f, " named \"{name}\"")?;
        }
        for comment in &self.comment {
            write!(f, " with comment \"{comment}\"")?;
        }
        if let Some(action) = &self.action {
            write!(f, " on file \"{action}\"")?;
        }
        if let Some(query) = &self.query {
            write!(f, " on query {}", &query)?;
        }
        for data in &self.data {
            write!(f, " with data {data}")?;
        }
        for (_, data) in &self.graph_data {
            write!(f, " and graph data {data}")?;
        }
        for result in &self.result {
            write!(f, " and expected result {result}")?;
        }
        Ok(())
    }
}

pub struct TestManifest {
    graph: Graph,
    tests_to_do: VecDeque<Term>,
    manifests_to_do: VecDeque<String>,
}

impl TestManifest {
    pub fn new<S: ToString>(manifest_urls: impl IntoIterator<Item = S>) -> Self {
        Self {
            graph: Graph::new(),
            tests_to_do: VecDeque::new(),
            manifests_to_do: manifest_urls
                .into_iter()
                .map(|url| url.to_string())
                .collect(),
        }
    }
}

impl Iterator for TestManifest {
    type Item = Result<Test>;

    fn next(&mut self) -> Option<Result<Test>> {
        loop {
            if let Some(next) = self.next_test() {
                return Some(next);
            }
            if let Err(e) = self.load_next_manifest()? {
                return Some(Err(e));
            }
        }
    }
}

impl TestManifest {
    fn next_test(&mut self) -> Option<Result<Test>> {
        let test_node = self.tests_to_do.pop_front()?;
        let test_node = match test_node {
            Term::NamedNode(n) => n,
            _ => {
                return Some(Err(anyhow!("Invalid test identifier. Got {test_node}")));
            }
        };

        let name = match self
            .graph
            .object_for_subject_predicate(&test_node, mf::NAME)
        {
            Some(TermRef::Literal(c)) => Some(c.value().to_string()),
            _ => None,
        };
        let kind = match self
            .graph
            .object_for_subject_predicate(&test_node, rdf::TYPE)
        {
            Some(TermRef::NamedNode(c)) => c.into_owned(),
            _ => {
                return Some(Err(anyhow!(
                    "The test {test_node} named {} has no rdf:type",
                    name.as_deref().unwrap_or("")
                )));
            }
        };
        let comment = match self
            .graph
            .object_for_subject_predicate(&test_node, rdfs::COMMENT)
        {
            Some(TermRef::Literal(c)) => Some(c.value().to_string()),
            _ => None,
        };
        let (action, query, update, data, graph_data, service_data) = match self
            .graph
            .object_for_subject_predicate(&test_node, mf::ACTION)
        {
            Some(TermRef::NamedNode(n)) => (
                Some(n.as_str().to_owned()),
                None,
                None,
                None,
                vec![],
                vec![],
            ),
            Some(TermRef::BlankNode(n)) => {
                let query = match self.graph.object_for_subject_predicate(n, qt::QUERY) {
                    Some(TermRef::NamedNode(q)) => Some(q.as_str().to_owned()),
                    _ => None,
                };
                let update = match self.graph.object_for_subject_predicate(n, ut::REQUEST) {
                    Some(TermRef::NamedNode(q)) => Some(q.as_str().to_owned()),
                    _ => None,
                };
                let data = match self
                    .graph
                    .object_for_subject_predicate(n, qt::DATA)
                    .or_else(|| self.graph.object_for_subject_predicate(n, ut::DATA))
                {
                    Some(TermRef::NamedNode(q)) => Some(q.as_str().to_owned()),
                    _ => None,
                };
                let graph_data = self
                    .graph
                    .objects_for_subject_predicate(n, qt::GRAPH_DATA)
                    .chain(self.graph.objects_for_subject_predicate(n, ut::GRAPH_DATA))
                    .filter_map(|g| match g {
                        TermRef::NamedNode(q) => Some((q.into_owned(), q.as_str().to_owned())),
                        TermRef::BlankNode(node) => {
                            if let Some(TermRef::NamedNode(graph)) =
                                self.graph.object_for_subject_predicate(node, ut::GRAPH)
                            {
                                if let Some(TermRef::Literal(name)) =
                                    self.graph.object_for_subject_predicate(node, rdfs::LABEL)
                                {
                                    Some((
                                        NamedNode::new(name.value()).unwrap(),
                                        graph.as_str().to_owned(),
                                    ))
                                } else {
                                    Some((graph.into_owned(), graph.as_str().to_owned()))
                                }
                            } else {
                                None
                            }
                        }
                        _ => None,
                    })
                    .collect();
                let service_data = self
                    .graph
                    .objects_for_subject_predicate(n, qt::SERVICE_DATA)
                    .filter_map(|g| match g {
                        TermRef::NamedNode(g) => Some(g.into()),
                        TermRef::BlankNode(g) => Some(g.into()),
                        _ => None,
                    })
                    .filter_map(|g: SubjectRef<'_>| {
                        if let (
                            Some(TermRef::NamedNode(endpoint)),
                            Some(TermRef::NamedNode(data)),
                        ) = (
                            self.graph.object_for_subject_predicate(g, qt::ENDPOINT),
                            self.graph.object_for_subject_predicate(g, qt::DATA),
                        ) {
                            Some((endpoint.as_str().to_owned(), data.as_str().to_owned()))
                        } else {
                            None
                        }
                    })
                    .collect();
                (None, query, update, data, graph_data, service_data)
            }
            Some(_) => return Some(Err(anyhow!("invalid action"))),
            None => {
                return Some(Err(anyhow!("action not found for test {test_node}")));
            }
        };
        let (result, result_graph_data) = match self
            .graph
            .object_for_subject_predicate(&test_node, mf::RESULT)
        {
            Some(TermRef::NamedNode(n)) => (Some(n.as_str().to_owned()), Vec::new()),
            Some(TermRef::BlankNode(n)) => (
                if let Some(TermRef::NamedNode(result)) =
                    self.graph.object_for_subject_predicate(n, ut::DATA)
                {
                    Some(result.as_str().to_owned())
                } else {
                    None
                },
                self.graph
                    .objects_for_subject_predicate(n, ut::GRAPH_DATA)
                    .filter_map(|g| match g {
                        TermRef::NamedNode(q) => Some((q.into_owned(), q.as_str().to_owned())),
                        TermRef::BlankNode(node) => {
                            if let Some(TermRef::NamedNode(graph)) =
                                self.graph.object_for_subject_predicate(node, ut::GRAPH)
                            {
                                if let Some(TermRef::Literal(name)) =
                                    self.graph.object_for_subject_predicate(node, rdfs::LABEL)
                                {
                                    Some((
                                        NamedNode::new(name.value()).unwrap(),
                                        graph.as_str().to_owned(),
                                    ))
                                } else {
                                    Some((graph.into_owned(), graph.as_str().to_owned()))
                                }
                            } else {
                                None
                            }
                        }
                        _ => None,
                    })
                    .collect(),
            ),
            Some(_) => return Some(Err(anyhow!("invalid result"))),
            None => (None, Vec::new()),
        };
        Some(Ok(Test {
            id: test_node,
            kind,
            name,
            comment,
            action,
            query,
            update,
            data,
            graph_data,
            service_data,
            result,
            result_graph_data,
        }))
    }

    fn load_next_manifest(&mut self) -> Option<Result<()>> {
        let url = self.manifests_to_do.pop_front()?;
        self.graph.clear();
        if let Err(error) = load_to_graph(&url, &mut self.graph) {
            return Some(Err(error));
        }

        let manifests = self
            .graph
            .subjects_for_predicate_object(rdf::TYPE, mf::MANIFEST)
            .collect::<Vec<_>>();
        if manifests.len() != 1 {
            return Some(Err(anyhow!(
                "The file {url} should contain a single manifest"
            )));
        }
        for manifest in manifests {
            match self
                .graph
                .object_for_subject_predicate(manifest, mf::INCLUDE)
            {
                Some(TermRef::BlankNode(list)) => {
                    self.manifests_to_do.extend(
                        RdfListIterator::iter(&self.graph, list.into()).filter_map(|m| match m {
                            Term::NamedNode(nm) => Some(nm.into_string()),
                            _ => None,
                        }),
                    );
                }
                Some(_) => return Some(Err(anyhow!("invalid tests list"))),
                None => (),
            }

            // New tests
            match self
                .graph
                .object_for_subject_predicate(manifest, mf::ENTRIES)
            {
                Some(TermRef::BlankNode(list)) => {
                    self.tests_to_do
                        .extend(RdfListIterator::iter(&self.graph, list.into()));
                }
                Some(term) => {
                    return Some(Err(anyhow!("Invalid tests list. Got term {term}")));
                }
                None => (),
            }
        }
        Some(Ok(()))
    }
}

struct RdfListIterator<'a> {
    graph: &'a Graph,
    current_node: Option<SubjectRef<'a>>,
}

impl<'a> RdfListIterator<'a> {
    fn iter(graph: &'a Graph, root: SubjectRef<'a>) -> RdfListIterator<'a> {
        RdfListIterator {
            graph,
            current_node: Some(root),
        }
    }
}

impl<'a> Iterator for RdfListIterator<'a> {
    type Item = Term;

    fn next(&mut self) -> Option<Term> {
        match self.current_node {
            Some(current) => {
                let result = self
                    .graph
                    .object_for_subject_predicate(current, rdf::FIRST)
                    .map(|v| v.into_owned());
                self.current_node =
                    match self.graph.object_for_subject_predicate(current, rdf::REST) {
                        Some(TermRef::NamedNode(n)) if n == rdf::NIL => None,
                        Some(TermRef::NamedNode(n)) => Some(n.into()),
                        Some(TermRef::BlankNode(n)) => Some(n.into()),
                        _ => None,
                    };
                result
            }
            None => None,
        }
    }
}