// Copyright 2015 Gomez Guillaume
//
// 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 consts::{END_INFO, FILE, FILE_COMMENT, MOD_COMMENT};
use std::collections::HashMap;
use std::fs::{remove_file, File, OpenOptions};
use std::io::{BufRead, BufReader, Write};
use std::iter;
use std::ops::Deref;
use std::path::Path;
use strip;
use types::{EventType, ParseResult, Type, TypeStruct};
use utils::{join, loop_over_files, remove_macro_parent, write_comment, write_file};

type Infos = HashMap<Option<String>, Vec<(Option<TypeStruct>, Vec<String>)>>;

fn gen_indent(indent: usize) -> String {
    iter::repeat("    ")
        .take(indent)
        .collect::<Vec<&str>>()
        .join("")
}

fn gen_indent_from(from: &str) -> String {
    for (i, c) in from.chars().enumerate() {
        if c != ' ' && c != '\t' {
            return gen_indent(i / 4);
        }
    }
    String::new()
}

/// Returns `true` in case a "// rustdoc-stripper-ignore-next-stop" was inserted.
fn regenerate_comment(
    is_file_comment: bool,
    position: usize,
    indent: usize,
    comment: &str,
    original_content: &mut Vec<String>,
    need_check_ignore_doc_comment: bool,
) -> bool {
    let mut need_to_add_ignore_next_comment_stop = false;
    if need_check_ignore_doc_comment && position > 0 {
        let prev = original_content[position - 1].trim();
        if strip::DOC_COMMENT_ID.iter().any(|d| prev.starts_with(d)) {
            need_to_add_ignore_next_comment_stop = true;
        }
    }
    let is_empty = comment.trim().is_empty();
    let read_indent = if is_file_comment {
        gen_indent(indent)
    } else {
        let tmp = original_content[position].clone();
        gen_indent_from(&tmp)
    };
    original_content.insert(
        position,
        format!(
            "{}{}{}{}",
            &read_indent,
            if is_file_comment { "//!" } else { "///" },
            if is_empty { "" } else { " " },
            if is_empty { "" } else { comment }
        ),
    );
    if need_to_add_ignore_next_comment_stop {
        original_content.insert(
            position,
            format!("{}{}", &read_indent, strip::IGNORE_NEXT_COMMENT_STOP,),
        );
    }
    need_to_add_ignore_next_comment_stop
}

#[allow(clippy::useless_let_if_seq)]
fn get_corresponding_type(
    elements: &[(Option<TypeStruct>, Vec<String>)],
    to_find: &Option<TypeStruct>,
    mut line: usize,
    decal: &mut usize,
    original_content: &mut Vec<String>,
    ignore_macros: bool,
) -> Option<usize> {
    if to_find.is_none() {
        return None;
    }
    let to_find = to_find.as_ref().unwrap();
    let mut pos = 0;

    while pos < elements.len() {
        if match elements[pos].0 {
            Some(ref a) => {
                // is true if a is a top level Type, or if is inside a macro and Type and name match
                /* The result is that if there is a struct defined inside a macro,
                the documentation (if it has) of that struct will be written inside the macro. */
                let ret = a == to_find || {
                    let mut tmp = to_find.clone();
                    remove_macro_parent(&mut tmp);
                    *a == tmp
                };

                // to detect variants
                if !ret
                    && to_find.ty == Type::Unknown
                    && to_find.parent.is_some()
                    && a.parent.is_some()
                    && a.parent == to_find.parent
                {
                    if match to_find.parent {
                        Some(ref p) => {
                            p.ty == Type::Struct || p.ty == Type::Enum || p.ty == Type::Use
                        }
                        None => false,
                    } {
                        let mut tmp = to_find.clone();
                        tmp.ty = Type::Variant;
                        a == &tmp
                    } else {
                        false
                    }
                } else {
                    ret
                }
            }
            _ => false,
        } {
            let mut file_comment = false;

            if !elements[pos].1.is_empty() && elements[pos].1[0].starts_with("//!") {
                line += 1;
                file_comment = true;
            } else {
                while line > 0
                    && (line + *decal) > 0
                    && original_content[line + *decal - 1]
                        .trim_start()
                        .starts_with('#')
                {
                    line -= 1;
                }
            }
            let mut first = true;
            for comment in elements[pos].1.iter().skip(usize::from(file_comment)) {
                let depth = if let Some(ref e) = elements[pos].0 {
                    e.get_depth(ignore_macros)
                } else {
                    0
                };
                if regenerate_comment(
                    file_comment,
                    line + *decal,
                    depth + 1,
                    comment,
                    original_content,
                    first,
                ) {
                    *decal += 1;
                }
                *decal += 1;
                first = false;
            }
            return Some(pos);
        }
        pos += 1;
    }
    None
}

// The hashmap key is `Some(file name)` or `None` for entries that ignore file name
pub fn regenerate_comments(
    work_dir: &Path,
    path: &str,
    infos: &mut Infos,
    ignore_macros: bool,
    ignore_doc_commented: bool,
) {
    if !infos.contains_key(&None) && !infos.contains_key(&Some(path.to_owned())) {
        return;
    }
    let full_path = work_dir.join(path);
    match strip::build_event_list(&full_path) {
        Ok(ref mut parse_result) => {
            // exact path match
            if let Some(v) = infos.get_mut(&Some(path.to_owned())) {
                do_regenerate(
                    &full_path,
                    parse_result,
                    v,
                    ignore_macros,
                    ignore_doc_commented,
                );
            }
            // apply to all files
            if let Some(v) = infos.get_mut(&None) {
                do_regenerate(
                    &full_path,
                    parse_result,
                    v,
                    ignore_macros,
                    ignore_doc_commented,
                );
            }
        }
        Err(e) => {
            println!("Error in file '{}': {}", path, e);
        }
    }
}

fn check_if_regen(it: usize, parse_result: &ParseResult, ignore_doc_commented: bool) -> bool {
    ignore_doc_commented
        && it > 0
        && matches!(
            parse_result.event_list[it - 1].event,
            EventType::Comment(_) | EventType::FileComment(_)
        )
}

fn do_regenerate(
    path: &Path,
    parse_result: &mut ParseResult,
    elements: &mut Vec<(Option<TypeStruct>, Vec<String>)>,
    ignore_macros: bool,
    ignore_doc_commented: bool,
) {
    let mut position = 0;
    let mut decal = 0;

    // first, we need to put back file comment
    for entry in elements.iter() {
        if entry.0.is_none() {
            let mut it = 0;

            while it < parse_result.original_content.len()
                && parse_result.original_content[it].starts_with('/')
            {
                it += 1;
            }
            if it > 0 {
                it += 1;
            }
            if it < parse_result.original_content.len() {
                for line in &entry.1 {
                    if line.trim().is_empty() {
                        parse_result.original_content.insert(it, "//!".to_string());
                    } else {
                        parse_result
                            .original_content
                            .insert(it, format!("//! {}", &line));
                    }
                    decal += 1;
                    it += 1;
                }
            }
            parse_result.original_content.insert(it, "".to_owned());
            decal += 1;
            break;
        }
        position += 1;
    }
    if position < elements.len() {
        elements.remove(position);
    }
    let mut waiting_type = None;
    let mut current = None;
    let mut it = 0;

    while it < parse_result.event_list.len() {
        match parse_result.event_list[it].event {
            EventType::Type(ref t) => {
                if t.ty != Type::Unknown {
                    waiting_type = Some(t.clone());
                    let tmp = {
                        let t = strip::add_to_type_scope(&current, &waiting_type);
                        if ignore_macros {
                            erase_macro_path(t)
                        } else {
                            t
                        }
                    };

                    if !check_if_regen(it, parse_result, ignore_doc_commented) {
                        if let Some(l) = get_corresponding_type(
                            elements,
                            &tmp,
                            parse_result.event_list[it].line,
                            &mut decal,
                            &mut parse_result.original_content,
                            ignore_macros,
                        ) {
                            elements.remove(l);
                        }
                    }
                } else if let Some(ref c) = current {
                    if c.ty == Type::Struct || c.ty == Type::Enum || c.ty == Type::Mod {
                        let tmp = Some(t.clone());
                        let cc = {
                            let t = strip::add_to_type_scope(&current, &tmp);
                            if ignore_macros {
                                erase_macro_path(t)
                            } else {
                                t
                            }
                        };

                        if !check_if_regen(it, parse_result, ignore_doc_commented) {
                            if let Some(l) = get_corresponding_type(
                                elements,
                                &cc,
                                parse_result.event_list[it].line,
                                &mut decal,
                                &mut parse_result.original_content,
                                ignore_macros,
                            ) {
                                elements.remove(l);
                            }
                        }
                    }
                }
            }
            EventType::InScope => {
                current = strip::add_to_type_scope(&current, &waiting_type);
                waiting_type = None;
            }
            EventType::OutScope => {
                current = strip::type_out_scope(&current);
                waiting_type = None;
            }
            _ => {}
        }
        it += 1;
    }
    rewrite_file(path, &parse_result.original_content);
}

fn rewrite_file(path: &Path, o_content: &[String]) {
    match File::create(path) {
        Ok(mut f) => {
            write!(f, "{}", o_content.join("\n")).unwrap();
        }
        Err(e) => {
            println!("Cannot open '{}': {}", path.display(), e);
        }
    }
}

fn parse_mod_line(line: &str) -> Option<TypeStruct> {
    let line = line
        .replace(FILE_COMMENT, "")
        .replace(MOD_COMMENT, "")
        .replace(END_INFO, "");
    if line.is_empty() {
        return None;
    }
    let parts: Vec<&str> = line.split("::").collect();
    let mut current = None;

    for part in parts {
        let elems: Vec<&str> = part.split(' ').filter(|x| !x.is_empty()).collect();

        current = strip::add_to_type_scope(
            &current.clone(),
            &Some(TypeStruct::new(
                Type::from(elems[0]),
                elems[elems.len() - 1],
            )),
        );
    }
    current
}

fn save_remainings(infos: &Infos, comment_file: &str) {
    let mut remainings = 0;

    for content in infos.values() {
        if !content.is_empty() {
            remainings += 1;
        }
    }
    if remainings < 1 {
        let _ = remove_file(comment_file);
        return;
    }
    match File::create(comment_file) {
        Ok(mut out_file) => {
            println!(
                "Some comments haven't been regenerated to the files. Saving them \
                      back to '{}'.",
                comment_file
            );
            for (key, content) in infos {
                if content.is_empty() {
                    continue;
                }
                // Set the name to "*" for entries that ignore file name
                let key = key.as_ref().map(|s| &s[..]).unwrap_or("*");
                let _ = writeln!(out_file, "{}", &write_file(key));
                for line in content {
                    if let Some(ref d) = line.0 {
                        let _ = writeln!(
                            out_file,
                            "{}",
                            write_comment(d, &join(&line.1, "\n"), false)
                        );
                    }
                }
            }
        }
        Err(e) => {
            println!(
                "An error occured while trying to open '{}': {}",
                comment_file, e
            );
        }
    }
}

pub fn regenerate_doc_comments(
    directory: &str,
    verbose: bool,
    comment_file: &str,
    ignore_macros: bool,
    ignore_doc_commented: bool,
) {
    // we start by storing files info
    let f = match OpenOptions::new().read(true).open(comment_file) {
        Ok(f) => f,
        Err(e) => {
            println!(
                "An error occured while trying to open '{}': {}",
                comment_file, e
            );
            return;
        }
    };
    let reader = BufReader::new(f);
    let lines = reader.lines().map(|line| line.unwrap());
    let mut infos = parse_cmts(lines, ignore_macros);
    let ignores: &[&str] = &[];

    loop_over_files(
        directory.as_ref(),
        &mut |w, s| regenerate_comments(w, s, &mut infos, ignore_macros, ignore_doc_commented),
        ignores,
        verbose,
    );
    save_remainings(&infos, comment_file);
}

fn sub_erase_macro_path(ty: Option<Box<TypeStruct>>, is_parent: bool) -> Option<Box<TypeStruct>> {
    match ty {
        Some(ref t) if is_parent => {
            if t.ty == Type::Macro {
                sub_erase_macro_path(t.clone().parent, true)
            } else {
                let mut tmp = t.clone();
                tmp.parent = sub_erase_macro_path(t.clone().parent, true);
                Some(tmp)
            }
        }
        Some(t) => {
            let mut tmp = t.clone();
            tmp.parent = sub_erase_macro_path(t.parent, true);
            Some(tmp)
        }
        None => None,
    }
}

fn erase_macro_path(ty: Option<TypeStruct>) -> Option<TypeStruct> {
    ty.map(|t| *sub_erase_macro_path(Some(Box::new(t)), false).unwrap())
}

pub fn parse_cmts<S, I>(lines: I, ignore_macros: bool) -> Infos
where
    S: Deref<Target = str>,
    I: Iterator<Item = S>,
{
    enum State {
        Initial,
        File {
            file: Option<String>,
            infos: Vec<(Option<TypeStruct>, Vec<String>)>,
            ty: Option<TypeStruct>,
            comments: Vec<String>,
        },
    }

    // Returns `Some(name)` if the line matches FILE
    // where name is Some for an actual file name and None for "*"
    // The "*" entries are to be applied regardless of file name
    #[allow(clippy::option_option)]
    fn line_file(line: &str) -> Option<Option<String>> {
        if let Some(after) = line.strip_prefix(FILE) {
            let name = after.replace(END_INFO, "");
            if name == "*" {
                Some(None)
            } else {
                Some(Some(name))
            }
        } else {
            None
        }
    }

    let mut ret = HashMap::new();
    let mut state = State::Initial;

    for line in lines {
        state = match state {
            State::Initial => {
                if let Some(file) = line_file(&line) {
                    State::File {
                        file,
                        infos: vec![],
                        ty: None,
                        comments: vec![],
                    }
                } else {
                    panic!("Unrecognized format on line: `{}`", line.deref());
                }
            }
            State::File {
                mut file,
                mut infos,
                mut ty,
                mut comments,
            } => {
                if let Some(new_file) = line_file(&line) {
                    if !comments.is_empty() {
                        infos.push((ty.take(), comments));
                        comments = vec![];
                    }
                    if !infos.is_empty() {
                        ret.insert(file, infos);
                        file = new_file;
                        infos = vec![];
                    }
                } else if line.starts_with(FILE_COMMENT) {
                    if let Some(ty) = ty.take() {
                        if !comments.is_empty() {
                            infos.push((Some(ty), comments));
                            comments = vec!["//!".to_owned()];
                        }
                    } else if !comments.is_empty() {
                        infos.push((None, comments));
                        comments = vec![];
                    }
                    ty = parse_mod_line(&line[..]);
                } else if line.starts_with(MOD_COMMENT) {
                    if !comments.is_empty() {
                        infos.push((ty, comments));
                        comments = vec![];
                    }
                    ty = parse_mod_line(&line[..]);
                } else {
                    comments.push(line[..].to_owned());
                }
                State::File {
                    file,
                    infos,
                    ty: if ignore_macros {
                        erase_macro_path(ty)
                    } else {
                        ty
                    },
                    comments,
                }
            }
        }
    }

    if let State::File {
        file,
        mut infos,
        ty,
        comments,
    } = state
    {
        if !comments.is_empty() {
            infos.push((ty, comments));
        }
        if !infos.is_empty() {
            ret.insert(file, infos);
        }
    }

    ret
}