extern crate bio;
#[macro_use]
extern crate serde_json;
#[macro_use]
extern crate lazy_static;

use bio::io::gff;
use ignore_result::Ignore;
use libflate::gzip::Decoder;
use multimap::MultiMap;
use rayon::prelude::*;
use regex::Regex;
use serde_json::value::Value;
use std::collections::HashMap;
use std::collections::HashSet;
use std::error::Error;
use std::fs::File;
use std::sync::{Arc, Mutex};

type HashGFF = HashMap<String, bio::io::gff::Record>;

pub enum CompareMode {
    Forward,
    Reverse,
}

pub struct CompareGFF {
    data1: Option<HashGFF>,
    data2: Option<HashGFF>,
    record_issues: bool,
    flexible_ids: bool,
    issues: Vec<String>,
}

impl CompareGFF {
    /// Creates a new, blank CompareGFF.
    pub fn new() -> Self {
        Self {
            data1: None,
            data2: None,
            record_issues: false,
            flexible_ids: true,
            issues: vec![],
        }
    }

    /// Changes the option to record issues in the result.
    pub fn record_issues(&mut self, do_record: bool) {
        self.record_issues = do_record;
    }

    /// Changes the option to create new IDs in case of duplicates.
    pub fn flexible_ids(&mut self, use_flexible_ids: bool) {
        self.flexible_ids = use_flexible_ids;
    }

    /// Creates a new CompareGFF with two files.
    pub fn new_from_files<S: Into<String>>(
        filename1: S,
        filename2: S,
    ) -> Result<Self, Box<dyn Error>> {
        let mut ret = Self::new();
        ret.load_gff(filename1, 1)?;
        ret.load_gff(filename2, 2)?;
        Ok(ret)
    }

    fn get_file_reader<S: Into<String>>(
        filename: S,
    ) -> Result<Box<dyn std::io::Read>, Box<dyn Error>> {
        lazy_static! {
            static ref RE_GZ: Regex =
                Regex::new(r#"\.gz(ip){0,1}$"#).expect("new_from_files: RE_GZ does not compile");
        }
        let filename: String = filename.into();
        if RE_GZ.is_match(&filename) {
            let file_stream = File::open(filename)?;
            let decoder = Decoder::new(file_stream)?;
            Ok(Box::new(decoder))
        } else {
            let file_stream = File::open(filename)?;
            Ok(Box::new(file_stream))
        }
    }

    pub fn load_gff<S: Into<String>>(
        &mut self,
        filename: S,
        data_set: u8,
    ) -> Result<(), Box<dyn Error>> {
        //let data = Some(self.read(Box::new(File::open(filename.into())?))?);
        let reader = Self::get_file_reader(filename)?;
        let data = Some(self.read(reader)?);
        match data_set {
            1 => self.data1 = data,
            2 => self.data2 = data,
            _ => {
                return Err(From::from(format!(
                    "Data set number not 1 or 2: {}",
                    data_set
                )))
            }
        }
        Ok(())
    }

    /// Generates the diff between the two loaded files.
    pub fn diff(&self) -> Result<Value, Box<dyn Error>> {
        let mut result = json!( {
            "changes" :[]
        });
        self.compare(CompareMode::Forward, &mut result)?;
        self.compare(CompareMode::Reverse, &mut result)?;
        if self.record_issues {
            result["issues"] = json!(self.issues);
        }
        Ok(result)
    }

    /// Sorts a comparison JSON. Potentially slow. Used in tests.
    pub fn sort_comparison(result: &mut Value) {
        match result["changes"].as_array_mut() {
            Some(changes) => {
                changes.par_sort_by(|a, b| {
                    let a = serde_json::to_string(a).unwrap();
                    let b = serde_json::to_string(b).unwrap();
                    a.partial_cmp(&b).unwrap()
                });
                result["changes"] = json!(changes);
            }
            None => {}
        }
    }

    pub fn diff_apollo(&self) -> Result<Value, Box<dyn Error>> {
        self.compare_apollo()
    }

    fn log_issue(&mut self, issue: String) {
        if self.record_issues {
            self.issues.push(issue);
        } else {
            eprintln!("{}", issue);
        }
    }

    fn unique_id(
        &mut self,
        ids: &mut HashSet<String>,
        id: String,
        entry: &bio::io::gff::Record,
    ) -> Result<String, String> {
        if !ids.contains(&id) {
            return Ok(id);
        }
        let mut id = id;
        if self.flexible_ids {
            let original_id = id.to_owned();
            id += &format!(
                "_{}_{}_{}",
                entry.feature_type(),
                entry.start(),
                entry.end()
            );
            if !ids.contains(&id) {
                self.log_issue(format!("Double ID {}, changed to {}", &original_id, &id));
                return Ok(id);
            }
        }
        return Err(format!("Double ID {}, not adding {:?}", &id, entry));
    }

    /// Reads a file from a Reader into a HashGFF hash table.
    fn read(&mut self, file: Box<dyn std::io::Read>) -> Result<HashGFF, Box<dyn Error>> {
        let mut reader = gff::Reader::new(file, gff::GffType::GFF3);

        //TODO check for double IDs?
        let mut ids: HashSet<String> = HashSet::new();
        let ret: HashMap<String, bio::io::gff::Record> = reader
            .records()
            .filter_map(|element| {
                let e = element.ok()?;
                let id = match self.unique_id(&mut ids, e.attributes().get("ID")?.to_string(), &e) {
                    Ok(id) => id,
                    Err(e) => {
                        self.log_issue(e);
                        return None;
                    }
                };
                ids.insert(id.clone());
                Some((id, e))
            })
            .collect();
        if ret.is_empty() {
            return Err(From::from(format!("Empty file or no gff file")));
        }
        Ok(ret)
    }

    /// Writes the GFF data. Used to construct a new file after diff.
    fn write(&self, file: Box<dyn std::io::Write>, data: &HashGFF) -> Result<(), Box<dyn Error>> {
        let mut writer = gff::Writer::new(file, gff::GffType::GFF3);
        for (_k, v) in data {
            writer.write(v)?;
        }
        Ok(())
    }

    pub fn write_data1(&self, file: Box<dyn std::io::Write>) -> Result<(), Box<dyn Error>> {
        match &self.data1 {
            Some(data1) => self.write(file, &data1),
            None => Err(From::from(format!("write_data1:: data1 is not set"))),
        }
    }

    /// Compares the attributes of two GFF elements.
    fn compare_attributes(
        &self,
        id: &String,
        key: &String,
        values: &Vec<String>,
        attrs: &MultiMap<String, String>,
        mode: CompareMode,
        result: &Arc<Mutex<&mut Value>>,
    ) {
        // Does attrs have that key at all?
        if !attrs.contains_key(key) {
            values.par_iter().for_each(|value|{
                let action = match mode {
                    CompareMode::Forward => "remove",
                    _ => "add",
                };
                let j = json!( {"action" : action , "what": "attribute" , "id" : id , "key":key.to_string() , "value" : value.to_string() } );
                result.lock().unwrap()["changes"]
                    .as_array_mut()
                    .unwrap()
                    .push(j);
            });
            return;
        }

        // attrs has the key, compare values
        let values2 = attrs.get_vec(key).unwrap();

        values2.par_iter().for_each(|value2|{
            if !values.contains(&value2) {
                let action = match mode {
                    CompareMode::Forward => "add",
                    _ => "remove",
                };
                let j = json!({ "action" : action , "what" : "attribute" , "id" : id , "key":key , "value" : value2 } );
                result.lock().unwrap()["changes"]
                    .as_array_mut()
                    .unwrap()
                    .push(j);
            }
        });

        match mode {
            CompareMode::Forward => {}
            CompareMode::Reverse => {
                values.par_iter().for_each(|value|{
                    if !values2.contains(&value) {
                        let j = json!({"action" : "add", "what" : "attribute" , "id" : id , "key":key , "value" : value });
                        result.lock().unwrap()["changes"]
                            .as_array_mut()
                            .unwrap()
                            .push(j);
                    }
                });
            }
        }
    }

    /// Compares the basic attributes (location, type etc.) of two GFF elements.
    fn compare_basics(
        &self,
        r1: &bio::io::gff::Record,
        r2: &bio::io::gff::Record,
        id: &str,
    ) -> Vec<Value> {
        let mut changes: Vec<Value> = vec![];
        if r1.seqname() != r2.seqname() {
            let j = json!({ "action" : "update" , "what" : "row" , "id" : id , "key" : "seqname" , "value" : r2.seqname() });
            changes.push(j);
        }
        if r1.source() != r2.source() {
            let j = json!( { "action" : "update" , "what" : "row" , "id" : id , "key" : "source" , "value" : r2.source() });
            changes.push(j);
        }
        if r1.feature_type() != r2.feature_type() {
            let j = json!( { "action" : "update" , "what" : "row" , "id" : id , "key" : "feature_type" , "value" : r2.feature_type() });
            changes.push(j);
        }
        if r1.start() != r2.start() {
            let j = json!( { "action" : "update" , "what" : "row" , "id" : id , "key" : "start" , "value" : r2.start().to_string() });
            changes.push(j);
        }
        if r1.end() != r2.end() {
            let j = json!( { "action" : "update" , "what" : "row" , "id" : id , "key" : "end" , "value" : r2.end().to_string() });
            changes.push(j);
        }
        if r1.score() != r2.score() {
            let j = json!( { "action" : "update" , "what" : "row" , "id" : id , "key" : "score" , "value" : r2.score() });
            changes.push(j);
        }
        if r1.strand() != r2.strand() {
            let mut strand: String;
            strand = ".".to_string();
            let s = r2.strand();
            if s.is_some() {
                strand = s.unwrap().strand_symbol().to_string();
            }
            let j = json!( { "action" : "update" , "what" : "row" , "id" : id , "key" : "strand" , "value" : strand });
            changes.push(j);
        }
        if r1.frame() != r2.frame() {
            let j = json!( { "action" : "update" , "what" : "row" , "id" : id , "key" : "frame" , "value" : r2.frame() });
            changes.push(j);
        }
        changes
    }

    /// Compares the two loaded GFF files.
    fn compare(&self, mode: CompareMode, result: &mut Value) -> Result<(), Box<dyn Error>> {
        let (data1, data2) = match (&self.data1, &self.data2) {
            (Some(data1), Some(data2)) => match mode {
                CompareMode::Forward => (data1, data2),
                CompareMode::Reverse => (data2, data1),
            },
            _ => return Err(From::from(format!("Both GFF sets need to be initialized"))),
        };
        let result = Arc::new(Mutex::new(result));
        data1.par_iter().for_each(|(id, r1)| {
            if data2.contains_key(id) {
                match mode {
                    CompareMode::Forward => {}
                    CompareMode::Reverse => return, // Already did that with CompareMode::Forward
                }
                let r2 = &data2[id];
                self.compare_basics(&r1, r2, id.as_str())
                    .par_iter()
                    .for_each(|change| {
                        result.lock().unwrap()["changes"]
                            .as_array_mut()
                            .unwrap()
                            .push(change.to_owned())
                    });

                let r1a = r1.attributes();
                let r2a = r2.attributes();
                for (key, value) in r1a {
                    self.compare_attributes(&id, key, value, r2a, CompareMode::Forward, &result);
                }

                for (key, value) in r2a {
                    self.compare_attributes(&id, key, value, r1a, CompareMode::Reverse, &result);
                }
            } else {
                match mode {
                    CompareMode::Forward => {
                        let mut o = json! ({"what":"row" , "action": "remove" , "id":id });
                        let s = serde_json::to_string(&r1).unwrap();
                        o["removed_element"] = serde_json::from_str(&s).unwrap();
                        result.lock().unwrap()["changes"]
                            .as_array_mut()
                            .unwrap()
                            .push(o);
                    }
                    CompareMode::Reverse => {
                        let mut o = json! ({"what":"row" , "action": "add" , "id":id });
                        let s = serde_json::to_string(&r1).unwrap();
                        o["added_element"] = serde_json::from_str(&s).unwrap();
                        result.lock().unwrap()["changes"]
                            .as_array_mut()
                            .unwrap()
                            .push(o);
                    }
                }
            }
        });
        Ok(())
    }

    fn get_root_parent_id(
        &self,
        data: &HashGFF,
        id: &String,
        seen: Option<HashSet<String>>,
    ) -> Option<String> {
        let mut seen: HashSet<String> = seen.unwrap_or(HashSet::new());
        if seen.contains(id) {
            return None; // circular ID chain, oh no
        }
        seen.insert(id.to_string());
        match data.get(id) {
            Some(element) => match element.attributes().get("Parent") {
                Some(parent_id) => self.get_root_parent_id(data, parent_id, Some(seen)),
                None => Some(id.to_string()),
            },
            None => None,
        }
    }

    fn infer_original_id_from_apollo(
        &self,
        data1: &HashGFF,
        data2: &HashGFF,
        apollo_element: &bio::io::gff::Record,
        issues: &mut Vec<String>,
    ) -> Option<String> {
        // Try orig_id
        match apollo_element.attributes().get("orig_id") {
            Some(orig_id) => {
                return match data1.get(orig_id) {
                    Some(_) => Some(orig_id.to_string()),
                    None => {
                        issues.push(format!(
                            "Original ID '{}' given in Apollo GFF is not in full dataset!",
                            orig_id
                        ));
                        None
                    }
                }
            }
            None => {}
        }

        // Find Apollo parent
        let apollo_id = apollo_element.attributes().get("ID")?;
        let apollo_parent_id = self.get_root_parent_id(data2, apollo_id, None)?;
        //let apollo_parent_element = data2.get(&apollo_parent_id)?;

        // Find any other Apollo element with that parent and an orig_id
        let some_apollo_parent_id = Some(apollo_parent_id.to_owned());
        let orig_parent_id = data2
            .iter()
            .filter(|(id, _element)| {
                self.get_root_parent_id(data2, id, None) == some_apollo_parent_id
            }) // Same Apollo parent
            .filter_map(|(_id, element)| element.attributes().get("orig_id")) // with orig_id
            .map(|s| s.to_string())
            .filter(|orig_id| data1.contains_key(orig_id)) // with orig_id that exists in original dataset
            .filter_map(|orig_id| self.get_root_parent_id(data1, &orig_id, None)) // get that original root parent
            .nth(0)?;

        // Get all (sub)children on that parent in the original
        let some_orig_parent_id = Some(orig_parent_id);
        let all_children_orig: HashGFF = data1
            .iter()
            .filter(|(_id, data)| data.seqname() == apollo_element.seqname()) // Same chromosome
            .filter(|(id, _data)| self.get_root_parent_id(data1, id, None) == some_orig_parent_id) // Same root parent
            .map(|(id, data)| (id.to_owned(), data.to_owned()))
            .collect();

        // Try original elements with that parent, of the same type
        let same_type: HashGFF = all_children_orig
            .iter()
            .filter(|(_id, data)| data.feature_type() == apollo_element.feature_type())
            .map(|(id, data)| (id.to_owned(), data.to_owned()))
            .collect();

        // Found one element with the same type and (root) parent in the original data, using that one
        if same_type.len() == 1 {
            return Some(
                same_type
                    .iter()
                    .map(|(id, _data)| id.to_owned())
                    .nth(0)
                    .unwrap(),
            );
        }

        // TODO try location?

        None
    }

    /// data1 is "full" GFF, data2 is Apollo GFF
    fn compare_apollo(&self) -> Result<Value, Box<dyn Error>> {
        let (data1, data2) = match (&self.data1, &self.data2) {
            (Some(data1), Some(data2)) => (data1, data2),
            _ => return Err(From::from(format!("Both GFF sets need to be initialized"))),
        };
        let mut issues: Vec<String> = self.issues.clone();
        let mut changes: Vec<Value> = vec![];

        let _re = Regex::new(r"-\d+$").unwrap();

        for (_id, apollo_element) in data2 {
            let _attrs = apollo_element.attributes();
            let original_id = match self.infer_original_id_from_apollo(
                data1,
                data2,
                &apollo_element,
                &mut issues,
            ) {
                Some(id) => id,
                None => {
                    issues.push(format!("No original ID found for {:?}", apollo_element));
                    continue;
                }
            };
            let original_parent_id = match data1.get(&original_id) {
                Some(e) => e.attributes().get("Parent"),
                None => None,
            };
            let original_element = match data1.get(&original_id) {
                Some(e) => e,
                None => {
                    issues.push(format!("No original element found for {}", &original_id));
                    continue;
                }
            };

            // Add/remove/change parent ID
            match (
                original_parent_id,
                original_element.attributes().get("Parent"),
            ) {
                (Some(apollo_opid), Some(original_opid)) => {
                    if *apollo_opid != *original_opid {
                        let j = json!({ "action":"update" , "what":"attribute" , "id" : original_id , "key":"Parent" , "value" : apollo_opid } );
                        changes.push(j);
                        let j = json!({ "action":"remove" , "what":"attribute" , "id" : original_id , "key":"Parent" , "value" : original_opid } );
                        changes.push(j);
                    }
                }
                (Some(apollo_opid), None) => {
                    let j = json!({ "action":"add" , "what":"attribute" , "id" : original_id , "key":"Parent" , "value" : apollo_opid } );
                    changes.push(j);
                }
                (None, Some(original_opid)) => {
                    let _j = json!({ "action":"remove" , "what":"attribute" , "id" : original_id , "key":"Parent" , "value" : original_opid } );
                    //changes.push(j); // IGNORE THIS
                }
                (None, None) => {}
            }

            self.compare_basics(&original_element, &apollo_element, original_id.as_str())
                .drain(..)
                .filter(|change| {
                    match (
                        change["action"].as_str(),
                        change["key"].as_str(),
                        change["value"].as_str(),
                    ) {
                        (Some("update"), Some("source"), Some(".")) => false,
                        _ => true, // Default
                    }
                })
                .for_each(|change| changes.push(change));
        }

        Ok(match self.record_issues {
            true => json!({"changes": changes, "issues": issues}),
            false => json!({ "changes": changes }),
        })
    }

    fn gff_from_json(j: &Value) -> Result<bio::io::gff::Record, String> {
        let mut ret = bio::io::gff::Record::new();
        Self::apply_diff_row_update(&json!({"key":"seqname","value":&j["seqname"]}), &mut ret)
            .ignore();
        Self::apply_diff_row_update(&json!({"key":"source","value":&j["source"]}), &mut ret)
            .ignore();
        Self::apply_diff_row_update(
            &json!({"key":"feature_type","value":&j["feature_type"]}),
            &mut ret,
        )
        .ignore();
        Self::apply_diff_row_update(&json!({"key":"start","value":&j["start"]}), &mut ret).ignore();
        Self::apply_diff_row_update(&json!({"key":"end","value":&j["end"]}), &mut ret).ignore();
        Self::apply_diff_row_update(&json!({"key":"score","value":&j["score"]}), &mut ret).ignore();
        Self::apply_diff_row_update(&json!({"key":"strand","value":&j["strand"]}), &mut ret)
            .ignore();
        Self::apply_diff_row_update(&json!({"key":"frame","value":&j["frame"]}), &mut ret).ignore();

        // Attributes
        match j["attributes"].as_object() {
            Some(attributes) => {
                attributes.iter().for_each(|(key, values)| {
                    match values.as_array() {
                        Some(values) => {
                            values
                                .iter()
                                .filter_map(|value| value.as_str())
                                .for_each(|value| {
                                    Self::apply_diff_attribute_add(
                                        &mut ret,
                                        key.to_string(),
                                        value.to_string(),
                                    )
                                    .ignore();
                                })
                        }
                        None => {} // No values?!?
                    }
                });
            }
            None => {} // No attributes
        }

        Ok(ret)
    }

    fn apply_diff_row_remove(change: &Value, data: &mut HashGFF) -> Result<(), String> {
        match change["id"].as_str() {
            Some(id) => {
                data.remove(id);
            }
            None => return Err(format!("apply_diff_row_remove: add row, but no id set")),
        }
        Ok(())
    }

    fn apply_diff_row_update(
        change: &Value,
        element: &mut bio::io::gff::Record,
    ) -> Result<(), String> {
        let value = match change["value"].as_str() {
            Some(v) => v.to_string(),
            None => match change["value"].as_i64() {
                Some(v) => v.to_string(),
                None => return Err(format!("apply_diff_row_update: No value in {}", &change)),
            },
        };
        match change["key"].as_str() {
            Some("seqname") => *element.seqname_mut() = value,
            Some("source") => *element.source_mut() = value,
            Some("feature_type") => *element.feature_type_mut() = value,
            Some("start") => *element.start_mut() = value.parse::<u64>().unwrap(),
            Some("end") => *element.end_mut() = value.parse::<u64>().unwrap(),
            Some("score") => *element.score_mut() = value,
            Some("strand") => *element.strand_mut() = value,
            Some("frame") => *element.frame_mut() = value,
            _ => {
                return Err(format!(
                    "apply_diff_row_update: Unknown/missing 'key' in {}",
                    change
                ))
            }
        }
        Ok(())
    }

    fn apply_diff_row_add_or_update(change: &Value, data: &mut HashGFF) -> Result<(), String> {
        match change["id"].as_str() {
            Some(id) => {
                let action = change["action"].as_str().unwrap_or("");
                let element = match action {
                    "add" => data
                        .entry(id.to_string())
                        .or_insert(Self::gff_from_json(&change["added_element"])?),
                    _ => match data.get_mut(&id.to_string()) {
                        Some(e) => e,
                        None => return Err(format!(
                            "apply_diff_row_add_or_update: {} ID {} does not appear in data set",
                            action, &id
                        )),
                    },
                };
                if action == "update" {
                    Self::apply_diff_row_update(change, element)?;
                }
                Ok(())
            }
            None => Err(format!(
                "apply_diff_row_add_or_update: Missing 'id' in {:?}",
                change
            )),
        }
    }

    fn apply_diff_rows(
        changes: &Vec<Value>,
        data: &mut HashGFF,
        action: &str,
    ) -> Result<(), Box<dyn Error>> {
        match changes
            .iter()
            .filter(|change| change["what"].as_str().unwrap_or("") == "row")
            .filter(|change| change["action"].as_str().unwrap_or("") == action)
            .map(|change| match change["action"].as_str() {
                Some("remove") => Self::apply_diff_row_remove(change, data),
                Some("update") | Some("add") => Self::apply_diff_row_add_or_update(change, data),
                Some(other) => Err(format!(
                    "apply_diff_rows: Unknown action {} in {:?}",
                    other, change
                )),
                _ => Err(format!("apply_diff_rows: No action in {:?}", change)),
            })
            .filter_map(|r| match r {
                Ok(_) => None,
                Err(e) => Some(e),
            })
            .nth(0)
        {
            Some(err) => Err(From::from(err)),
            None => Ok(()),
        }
    }

    fn apply_diff_attribute_add(
        gff: &mut bio::io::gff::Record,
        key: String,
        value: String,
    ) -> Result<(), String> {
        gff.attributes_mut().insert(key, value);
        Ok(())
    }

    fn apply_diff_attribute_remove(
        gff: &mut bio::io::gff::Record,
        key: String,
        value: String,
    ) -> Result<(), String> {
        match gff.attributes_mut().get_vec_mut(&key) {
            Some(v) => {
                v.retain(|x| *x != value);
                Ok(())
            }
            None => Err(format!(
                "No attribute {}/{} to remove from {:?}",
                key, value, gff
            )),
        }
    }

    fn apply_diff_attributes(
        changes: &Vec<Value>,
        data: &mut HashGFF,
        action: &str,
    ) -> Result<(), Box<dyn Error>> {
        match changes
            .iter()
            .filter(|change| change["what"].as_str().unwrap_or("") == "attribute")
            .filter(|change| change["action"].as_str().unwrap_or("") == action)
            .map(|change| {
                let id = match change["id"].as_str() {
                    Some(id) => id.to_string(),
                    None => return Err(format!("apply_diff_attributes: No ID given: {}", change)),
                };
                let element = match data.get_mut(&id) {
                    Some(e) => e,
                    None => {
                        return Err(format!(
                            "apply_diff_attributes: ID {} not found in GFF1",
                            id
                        ))
                    }
                };
                let key = match change["key"].as_str() {
                    Some(s) => s.to_string(),
                    None => return Err(format!("apply_diff_attributes: No key given: {}", change)),
                };
                let value = match change["value"].as_str() {
                    Some(s) => s.to_string(),
                    None => {
                        return Err(format!("apply_diff_attributes: No value given: {}", change))
                    }
                };
                match change["action"].as_str() {
                    Some("add") => Self::apply_diff_attribute_add(element, key, value),
                    Some("remove") => Self::apply_diff_attribute_remove(element, key, value),
                    Some(other) => Err(format!(
                        "apply_diff_attributes: Unknown action {} in {:?}",
                        other, change
                    )),
                    _ => Err(format!("apply_diff_attributes: No action in {:?}", change)),
                }
            })
            .filter_map(|r| match r {
                Ok(_) => None,
                Err(e) => Some(e),
            })
            .nth(0)
        {
            Some(err) => Err(From::from(err)),
            None => Ok(()),
        }
    }

    /// Applies the given diff to the data loaded into the gff 1 slot.
    pub fn apply_diff(&mut self, diff: &Value) -> Result<&HashGFF, Box<dyn Error>> {
        let changes = match diff["changes"].as_array() {
            Some(changes) => changes,
            None => return Err(From::from(format!("No changes in diff"))),
        };
        let data = match self.data1.as_mut() {
            Some(data) => data,
            _ => return Err(From::from(format!("GFF set 1 needs to be initialized"))),
        };
        Self::apply_diff_rows(&changes, data, "remove")?;
        Self::apply_diff_rows(&changes, data, "add")?;
        Self::apply_diff_rows(&changes, data, "update")?;
        Self::apply_diff_attributes(&changes, data, "remove")?;
        Self::apply_diff_attributes(&changes, data, "add")?;
        Self::apply_diff_attributes(&changes, data, "update")?;
        Ok(data)
    }
}

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

    /// This computes a diff between two test GFF files, then compares it with the expected result (also a file).
    /// Then, it applies the diff to the original GFF file (#1), and diffs the modified GFF to the #2 GFF.
    /// This should yield no changes
    fn compare_expected(dir: &str) {
        let gff_file1 = format!("test/{}/core.gff", dir);
        let gff_file2 = format!("test/{}/cap.gff", dir);
        let expected_file = format!("test/{}/expected.json", dir);
        let mut cg = CompareGFF::new(); //_from_files(gff_file1, gff_file2).unwrap();
        cg.record_issues(true);
        cg.load_gff(gff_file1, 1).unwrap();
        cg.load_gff(gff_file2, 2).unwrap();
        let mut diff = cg.diff().unwrap();
        let expected = fs::read_to_string(expected_file).unwrap();
        let mut expected: Value = serde_json::from_str(&expected).unwrap();
        CompareGFF::sort_comparison(&mut diff);
        CompareGFF::sort_comparison(&mut expected);
        assert_eq!(diff["changes"], expected["changes"]);

        // Apply diff to data2
        cg.apply_diff(&diff).unwrap();
        let diff = cg.diff().unwrap();
        assert_eq!(diff["changes"].as_array().unwrap().len(), 0);
    }

    #[test]
    fn attribute_added() {
        let id: String = "the_id".to_string();
        let key: String = "the_key".to_string();
        let values = vec!["value1".to_string(), "value3".to_string()];
        let mut attrs = MultiMap::new();
        let mut result = json! ({"changes":[]});
        let result = Arc::new(Mutex::new(&mut result));

        attrs.insert("the_key".to_string(), "value1".to_string());
        attrs.insert("the_key".to_string(), "value2".to_string());
        attrs.insert("the_key".to_string(), "value3".to_string());

        CompareGFF::new().compare_attributes(
            &id,
            &key,
            &values,
            &attrs,
            CompareMode::Forward,
            &result,
        );

        let expected = json! ({ "changes" : [ { "action" : "add", "what": "attribute", "id" : id , "key":key , "value" : "value2" } ] });
        assert_eq!(**result.lock().unwrap(), expected);
    }

    #[test]
    fn added_exon() {
        compare_expected("added_exon");
    }

    #[test]
    fn alter_exon() {
        compare_expected("alter_exon");
    }

    #[test]
    fn gene_in_intron() {
        compare_expected("gene_in_intron");
    }

    #[test]
    fn gene_merge() {
        compare_expected("gene_merge");
    }

    #[test]
    fn gene_split() {
        compare_expected("gene_split");
    }

    #[test]
    fn gene_validation_3exons_ok() {
        // No change, actually
        compare_expected("gene_validation_3exons_ok");
    }

    #[test]
    fn gene_validation_no_start() {
        compare_expected("gene_validation_no_start");
    }

    #[test]
    fn gene_validation_no_stop() {
        compare_expected("gene_validation_no_stop");
    }

    #[test]
    fn gene_validation_ok() {
        compare_expected("gene_validation_ok");
    }

    #[test]
    fn iso_form() {
        compare_expected("iso_form");
    }

    #[test]
    fn iso_form_lost() {
        compare_expected("iso_form_lost");
    }

    #[test]
    fn new_gene() {
        compare_expected("new_gene");
    }

    #[test]
    fn no_change() {
        // There is actually a change here
        compare_expected("no_change");
    }

    #[test]
    fn no_change_isoforms() {
        compare_expected("no_change_isoforms");
    }

    #[test]
    fn remove_exon() {
        compare_expected("remove_exon");
    }

    #[test]
    fn utr_change() {
        compare_expected("utr_change");
    }
}