// Std
use std::io::Write;

// Internal
use app::parser::Parser;
use args::{ArgSettings, OptBuilder};
use shell::Shell;

macro_rules! w {
    ($buf:expr, $to_w:expr) => {
        match $buf.write_all($to_w) {
            Ok(..) => (),
            Err(..) => panic!("Failed to write to file completions file"),
        }
    };
}

pub struct ComplGen<'a, 'b>
    where 'a: 'b
{
    p: &'b Parser<'a, 'b>,
}

impl<'a, 'b> ComplGen<'a, 'b> {
    pub fn new(p: &'b Parser<'a, 'b>) -> Self {
        ComplGen { p: p }
    }

    pub fn generate<W: Write>(&self, for_shell: Shell, buf: &mut W) {
        match for_shell {
            Shell::Bash => self.gen_bash(buf),
            Shell::Fish => self.gen_fish(buf),
        }
    }

    fn gen_bash<W: Write>(&self, buf: &mut W) {
        w!(buf,
           format!("_{name}() {{
    local i cur prev opts cmds
    COMPREPLY=()
    cur=\"${{COMP_WORDS[COMP_CWORD]}}\"
    prev=\"${{COMP_WORDS[COMP_CWORD-1]}}\"
    cmd=\"\"
    opts=\"\"

    for i in ${{COMP_WORDS[@]}}
    do
        case \"${{i}}\" in
            {name})
                cmd=\"{name}\"
                ;;
            {subcmds}
            *)
                ;;
        esac
    done

    case \"${{cmd}}\" in
        {name})
            opts=\"{name_opts}\"
            if [[ ${{cur}} == -* || ${{COMP_CWORD}} -eq 1 ]] ; then
                COMPREPLY=( $(compgen -W \"${{opts}}\" -- ${{cur}}) )
                return 0
            fi
            case \"${{prev}}\" in
                {name_opts_details}
                *)
                    COMPREPLY=()
                    ;;
            esac
            COMPREPLY=( $(compgen -W \"${{opts}}\" -- ${{cur}}) )
            return 0
            ;;
        {subcmd_details}
    esac
}}

complete -F _{name} {name}
",
                   name = self.p.meta.bin_name.as_ref().unwrap(),
                   name_opts = self.all_options_for_path(self.p.meta.bin_name.as_ref().unwrap()),
                   name_opts_details =
                       self.option_details_for_path(self.p.meta.bin_name.as_ref().unwrap()),
                   subcmds = self.all_subcommands(),
                   subcmd_details = self.subcommand_details())
               .as_bytes());
    }

    fn all_subcommands(&self) -> String {
        let mut subcmds = String::new();
        let scs = get_all_subcommands(self.p);

        for sc in &scs {
            subcmds = format!("{}
            {name})
                cmd+=\"_{name}\"
                ;;",
                              subcmds,
                              name = sc.replace("-", "_"));
        }

        subcmds
    }

    fn subcommand_details(&self) -> String {
        let mut subcmd_dets = String::new();
        let mut scs = get_all_subcommand_paths(self.p, true);
        scs.sort();
        scs.dedup();

        for sc in &scs {
            subcmd_dets = format!("{}
        {subcmd})
            opts=\"{sc_opts}\"
            if [[ ${{cur}} == -* || ${{COMP_CWORD}} -eq {level} ]] ; then
                COMPREPLY=( $(compgen -W \"${{opts}}\" -- ${{cur}}) )
                return 0
            fi
            case \"${{prev}}\" in
                {opts_details}
                *)
                    COMPREPLY=()
                    ;;
            esac
            COMPREPLY=( $(compgen -W \"${{opts}}\" -- ${{cur}}) )
            return 0
            ;;",
                                  subcmd_dets,
                                  subcmd = sc.replace("-", "_"),
                                  sc_opts = self.all_options_for_path(&*sc),
                                  level = sc.split("_").map(|_| 1).fold(0, |acc, n| acc + n),
                                  opts_details = self.option_details_for_path(&*sc));
        }

        subcmd_dets
    }

    fn all_options_for_path(&self, path: &str) -> String {
        let mut p = self.p;
        for sc in path.split('_').skip(1) {
            debugln!("iter;sc={}", sc);
            p = &p.subcommands
                .iter()
                .find(|s| {
                    s.p.meta.name == sc ||
                    (s.p.meta.aliases.is_some() &&
                     s.p
                        .meta
                        .aliases
                        .as_ref()
                        .unwrap()
                        .iter()
                        .any(|&(n, _)| n == sc))
                })
                .unwrap()
                .p;
        }
        let mut opts = p.short_list.iter().fold(String::new(), |acc, s| format!("{} -{}", acc, s));
        opts = format!("{} {}",
                       opts,
                       p.long_list
                           .iter()
                           .fold(String::new(), |acc, l| format!("{} --{}", acc, l)));
        opts = format!("{} {}",
                       opts,
                       p.positionals
                           .values()
                           .fold(String::new(), |acc, p| format!("{} {}", acc, p)));
        opts = format!("{} {}",
                       opts,
                       p.subcommands
                           .iter()
                           .fold(String::new(), |acc, s| format!("{} {}", acc, s.p.meta.name)));
        for sc in &p.subcommands {
            if let Some(ref aliases) = sc.p.meta.aliases {
                opts = format!("{} {}",
                               opts,
                               aliases.iter()
                                   .map(|&(n, _)| n)
                                   .fold(String::new(), |acc, a| format!("{} {}", acc, a)));
            }
        }
        opts
    }

    fn option_details_for_path(&self, path: &str) -> String {
        let mut p = self.p;
        for sc in path.split('_').skip(1) {
            debugln!("iter;sc={}", sc);
            p = &p.subcommands
                .iter()
                .find(|s| {
                    s.p.meta.name == sc ||
                    (s.p.meta.aliases.is_some() &&
                     s.p
                        .meta
                        .aliases
                        .as_ref()
                        .unwrap()
                        .iter()
                        .any(|&(n, _)| n == sc))
                })
                .unwrap()
                .p;
        }
        let mut opts = String::new();
        for o in &p.opts {
            if let Some(l) = o.long {
                opts = format!("{}
                --{})
                    COMPREPLY=({})
                    return 0
                    ;;",
                               opts,
                               l,
                               vals_for(o));
            }
            if let Some(s) = o.short {
                opts = format!("{}
                    -{})
                    COMPREPLY=({})
                    return 0
                    ;;",
                               opts,
                               s,
                               vals_for(o));
            }
        }
        opts
    }

    fn gen_fish<W: Write>(&self, buf: &mut W) {
        let command = self.p.meta.bin_name.as_ref().unwrap();
        let subcommands: Vec<_> = get_all_subcommands(self.p);
        let has_subcommands = subcommands.len() > 1;

        // function to detect subcommand
        let detect_subcommand_function = if has_subcommands {
            format!(
r#"function __fish_{}_no_subcommand --description "Test if there isn't given a subcommand"
    for i in (commandline -opc)
        if contains -- $i {}
            return 1
        end
    end
    return 0
end
"#, command, subcommands.join(" "))
        } else {
            "".to_string()
        };

        let mut buffer = detect_subcommand_function;
        gen_fish_inner(command, self, vec![], &mut buffer, has_subcommands);
        w!(buf, buffer.as_bytes());
    }
}

pub fn get_all_subcommands(p: &Parser) -> Vec<String> {
    let mut subcmds = vec![];
    if !p.has_subcommands() {
        let mut ret = vec![p.meta.name.clone()];
        if let Some(ref aliases) = p.meta.aliases {
            for &(n, _) in aliases {
                ret.push(n.to_owned());
            }
        }
        return ret;
    }
    for sc in &p.subcommands {
        if let Some(ref aliases) = sc.p.meta.aliases {
            for &(n, _) in aliases {
                subcmds.push(n.to_owned());
            }
        }
        subcmds.push(sc.p.meta.name.clone());
    }
    for sc_v in p.subcommands.iter().map(|s| get_all_subcommands(&s.p)) {
        subcmds.extend(sc_v);
    }
    subcmds.sort();
    subcmds.dedup();
    subcmds
}

pub fn get_all_subcommand_paths(p: &Parser, first: bool) -> Vec<String> {
    let mut subcmds = vec![];
    if !p.has_subcommands() {
        if !first {
            let name = &*p.meta.name;
            let path = p.meta.bin_name.as_ref().unwrap().clone().replace(" ", "_");
            let mut ret = vec![path.clone()];
            if let Some(ref aliases) = p.meta.aliases {
                for &(n, _) in aliases {
                    ret.push(path.replace(name, n));
                }
            }
            return ret;
        }
        return vec![];
    }
    for sc in &p.subcommands {
        let name = &*sc.p.meta.name;
        let path = sc.p.meta.bin_name.as_ref().unwrap().clone().replace(" ", "_");
        subcmds.push(path.clone());
        if let Some(ref aliases) = sc.p.meta.aliases {
            for &(n, _) in aliases {
                subcmds.push(path.replace(name, n));
            }
        }
    }
    for sc_v in p.subcommands.iter().map(|s| get_all_subcommand_paths(&s.p, false)) {
        subcmds.extend(sc_v);
    }
    subcmds
}

fn vals_for(o: &OptBuilder) -> String {
    use args::AnyArg;
    let mut ret = String::new();
    let mut needs_quotes = true;
    if let Some(vals) = o.possible_vals() {
        needs_quotes = false;
        ret = format!("$(compgen -W \"{}\" -- ${{cur}})", vals.join(" "));
    } else if let Some(vec) = o.val_names() {
        let mut it = vec.iter().peekable();
        while let Some((_, val)) = it.next() {
            ret = format!("{}<{}>{}",
                          ret,
                          val,
                          if it.peek().is_some() { " " } else { "" });
        }
        let num = vec.len();
        if o.is_set(ArgSettings::Multiple) && num == 1 {
            ret = format!("{}...", ret);
        }
    } else if let Some(num) = o.num_vals() {
        let mut it = (0..num).peekable();
        while let Some(_) = it.next() {
            ret = format!("{}<{}>{}",
                          ret,
                          o.name(),
                          if it.peek().is_some() { " " } else { "" });
        }
        if o.is_set(ArgSettings::Multiple) && num == 1 {
            ret = format!("{}...", ret);
        }
    } else {
        ret = format!("<{}>", o.name());
        if o.is_set(ArgSettings::Multiple) {
            ret = format!("{}...", ret);
        }
    }
    if needs_quotes {
        ret = format!("\"{}\"", ret);
    }
    ret
}

fn gen_fish_inner(root_command: &str,
                  comp_gen: &ComplGen,
                  parent_cmds: Vec<&String>,
                  buffer: &mut String,
                  has_no_subcommand_fn: bool) {
    // example :
    //
    // complete
    //      -c {command}
    //      -d "{description}"
    //      -s {short}
    //      -l {long}
    //      -a "{possible_arguments}"
    //      -r # if require parameter
    //      -f # don't use file completion
    //      -n "__fish_seen_subcommand_from install" # complete for subcommand "install"

    let command = &comp_gen.p.meta.name;
    let subcommands: Vec<_> = get_all_subcommands(comp_gen.p);

    for option in &comp_gen.p.opts {
        let mut template = format!("complete -c {}", root_command);
        if !parent_cmds.is_empty() {
            template.push_str(format!(" -n '__fish_seen_subcommand_from {}'", command).as_str());
        } else if has_no_subcommand_fn {
            template.push_str(format!(" -n '__fish_{}_no_subcommand'",
                                      comp_gen.p.meta.bin_name.as_ref().unwrap())
                .as_str());
        }
        if let Some(data) = option.short {
            template.push_str(format!(" -s {}", data).as_str());
        }
        if let Some(data) = option.long {
            template.push_str(format!(" -l {}", data).as_str());
        }
        if let Some(data) = option.help {
            template.push_str(format!(" -d '{}'", data).as_str());
        }
        if let Some(ref data) = option.possible_vals {
            template.push_str(format!(" -r -f -a '{}'", data.join(" ")).as_str());
        }
        buffer.push_str(template.as_str());
        buffer.push_str("\n");
    }

    for flag in &comp_gen.p.flags {
        let mut template = format!("complete -c {}", root_command);
        if !parent_cmds.is_empty() {
            template.push_str(format!(" -n '__fish_seen_subcommand_from {}'", command).as_str());
        } else if has_no_subcommand_fn {
            template.push_str(format!(" -n '__fish_{}_no_subcommand'",
                                      comp_gen.p.meta.bin_name.as_ref().unwrap())
                .as_str());
        }
        if let Some(data) = flag.short {
            template.push_str(format!(" -s {}", data).as_str());
        }
        if let Some(data) = flag.long {
            template.push_str(format!(" -l {}", data).as_str());
        }
        if let Some(data) = flag.help {
            template.push_str(format!(" -d '{}'", data).as_str());
        }
        buffer.push_str(template.as_str());
        buffer.push_str("\n");
    }

    if subcommands.len() > 1 {
        for subcommand in subcommands {
            let mut template = format!("complete -c {}", root_command);
            if !parent_cmds.is_empty() {
                template.push_str(format!(" -n '__fish_seen_subcommand_from {}'",
                                          subcommand)
                    .as_str());
            } else if has_no_subcommand_fn {
                template.push_str(format!(" -n '__fish_{}_no_subcommand'",
                                          comp_gen.p.meta.bin_name.as_ref().unwrap())
                    .as_str());
            }
            template.push_str(" -f");
            template.push_str(format!(" -a '{}'", subcommand).as_str());
            buffer.push_str(template.as_str());
            buffer.push_str("\n");
        }
    }

    // generate options of subcommands
    for subcommand in &comp_gen.p.subcommands {
        let sub_comp_gen = ComplGen::new(&subcommand.p);
        let mut sub_parent_cmds = parent_cmds.clone();
        sub_parent_cmds.push(command);
        gen_fish_inner(root_command,
                       &sub_comp_gen,
                       sub_parent_cmds,
                       buffer,
                       has_no_subcommand_fn);
    }
}