extern crate base64;
extern crate byteorder;
extern crate clap;
extern crate image;
extern crate imageproc;
extern crate itertools;
extern crate md5;
extern crate num_enum;
extern crate num_traits;
extern crate reqwest;
extern crate rusttype;
extern crate termcolor;
extern crate xdg;

use std::error::Error as StdError;
use std::fmt;

macro_rules! error_froms {
    ($tname:ty, $($ename:ident : $fty:ty => $res:expr,)*) => {
        $(
            impl From<$fty> for $tname {
                fn from($ename: $fty) -> Self {
                    $res
                }
            }
        )*
    }
}

mod api;
mod bt;
mod cache;
mod output;
mod render;

use clap::{App, Arg, ArgMatches};

use api::{Api, Profession, Skill};
use bt::{BuildTemplate, ExtraData, Legend, TraitChoice, Traitline, CODE_REVENANT};
use render::RenderError;

/// The name of this application.
///
/// This is used for example in the cache path.
const APP_NAME: &str = "kondou";

/// Return value indicating that a requested resource could not be found.
#[derive(Debug, Clone)]
enum NotFound {
    /// Used when the requested profession can not be found.
    ///
    /// The argument is the requested profession.
    Profession(String),
    /// Used when a skill given by its ID could not be found.
    ///
    /// The argument is the requested skill id.
    SkillId(u32),
    /// Used when a skill given by its name could not be found.
    ///
    /// The argument is the requested skill name.
    SkillName(String),
    /// Used when a specialization could not be found.
    ///
    /// The argument is the requested specialization.
    Specialization(String),
}

impl fmt::Display for NotFound {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            NotFound::Profession(ref name) => {
                write!(f, "the profession '{}' could not be found", name)
            }
            NotFound::SkillId(id) => write!(f, "the skill with the ID '{}' was not found", id),
            NotFound::SkillName(ref name) => {
                write!(f, "the skill with the name '{}' was not found", name)
            }
            NotFound::Specialization(ref name) => write!(
                f,
                "the specialization with the name '{}' was not found",
                name
            ),
        }
    }
}

impl StdError for NotFound {}

/// A top-level result.
///
/// We use a dynamic error dispatch here for two reasons:
/// 1. The only thing that we really do here is displaying the error to the user.
/// 2. We don't want yet another error kind with a lot of kinds.
type MainResult<T> = Result<T, Box<dyn StdError>>;

/// A trait for containers that only contain a single item.
trait SingleContainer<T> {
    /// Extract the single element by consuming the container.
    fn single(self) -> T;
}

impl<T> SingleContainer<T> for Vec<T> {
    fn single(self) -> T {
        assert_eq!(self.len(), 1, "this container must have exactly 1 element.");
        self.into_iter().next().unwrap()
    }
}

/// Find the profession by the given name.
fn find_profession(api: &mut Api, name: &str) -> MainResult<Profession> {
    let profession_ids = api.get_profession_ids()?;
    let lower_name = name.to_lowercase();
    let profession_id = profession_ids
        .iter()
        .find(|id| id.to_lowercase() == lower_name)
        .ok_or_else(|| NotFound::Profession(name.to_owned()))?
        .clone();

    Ok(api.get_professions(&[profession_id])?.single())
}

/// Resolve a skill.
///
/// `text` can either be a skill name, in which case all skills of the profession will be searched.
/// Alternatively, it can also be a numeric ID, in which case it will be requested directly.
fn resolve_skill(api: &mut Api, profession: &Profession, text: &str) -> MainResult<Skill> {
    // Try it as an ID first
    let numeric = text.parse::<u32>();
    if let Ok(num_id) = numeric {
        let exists = profession.skills.iter().any(|s| s.id == num_id);
        if exists {
            return Ok(api.get_skills(&[num_id])?.single());
        } else {
            return Err(NotFound::SkillId(num_id).into());
        }
    }

    // Check all names of the profession skills
    let all_ids = profession.skills.iter().map(|s| s.id).collect::<Vec<_>>();
    let all_skills = api.get_skills(&all_ids)?;
    let lower_text = text.to_lowercase();
    all_skills
        .into_iter()
        .find(|s| s.name.to_lowercase().contains(&lower_text))
        .ok_or_else(|| NotFound::SkillName(text.to_owned()).into())
}

/// Resolve a traitline.
///
/// `text` must be in the `"name:choice1:choice2:choice3"` format.
fn resolve_traitline(api: &mut Api, profession: &Profession, text: &str) -> MainResult<Traitline> {
    let parts = text.split(':').collect::<Vec<_>>();
    assert_eq!(
        parts.len(),
        4,
        "invalid text format passed to resolve_traitline"
    );

    let name = parts[0];
    let lower_name = name.to_lowercase();
    let spec = api
        .get_specializations(&profession.specializations)?
        .into_iter()
        .find(|s| s.name.to_lowercase() == lower_name)
        .ok_or_else(|| NotFound::Specialization(name.to_owned()))?;

    let mut choices = [TraitChoice::None; 3];
    for (i, text_choice) in parts.iter().skip(1).enumerate() {
        let choice = text_choice
            .parse()
            .expect("Argument validation failed us, there is an invalid value here");
        choices[i] = choice;
    }
    Ok((spec, choices))
}

/// Create the build template by manually combining the given skills/traitlines from the CLI.
fn run_searching(api: &mut Api, matches: &ArgMatches) -> MainResult<BuildTemplate> {
    let requested_profession = matches
        .value_of("profession")
        .expect("clap handles missing argument");

    let profession = find_profession(api, requested_profession)?;

    let legends = matches
        .values_of("legend")
        .map(Iterator::collect::<Vec<_>>)
        .unwrap_or_default()
        .into_iter()
        .map(str::parse)
        .map(Result::unwrap)
        .collect::<Vec<_>>();

    let extra_data = if profession.code == CODE_REVENANT {
        let mut array_legends = [Legend::None; 4];
        for (i, l) in legends.iter().enumerate() {
            array_legends[i] = *l;
        }
        ExtraData::Legends(array_legends)
    } else {
        ExtraData::None
    };

    let skills = if profession.code != CODE_REVENANT {
        matches
            .values_of("skill")
            .map(Iterator::collect::<Vec<_>>)
            .unwrap_or_default()
            .into_iter()
            .map(|s| resolve_skill(api, &profession, s))
            .collect::<Result<Vec<_>, _>>()?
    } else if let Some(l) = legends.first() {
        let l = api.get_legends(&[l.api_id().unwrap()])?.single();
        let mut result = Vec::new();
        for skill_id in (&[l.heal]).iter().chain(&l.utilities).chain(&[l.elite]) {
            let skill = api.get_skills(&[*skill_id])?.single();
            result.push(skill);
        }
        result
    } else {
        Vec::new()
    };

    let traitlines = matches
        .values_of("traitline")
        .map(Iterator::collect::<Vec<_>>)
        .unwrap_or_default()
        .into_iter()
        .map(|t| resolve_traitline(api, &profession, t))
        .collect::<Result<Vec<_>, _>>()?;

    assert!(skills.len() <= bt::SKILL_COUNT, "got too many skills");
    assert!(
        traitlines.len() <= bt::TRAITLINE_COUNT,
        "got too many traitlines"
    );

    let build = BuildTemplate::new(profession, &skills, &traitlines, extra_data)
        .expect("BuildTemplate could not be constructed");

    Ok(build)
}

/// Create the build template by parsing a chat link.
fn run_chatlink(api: &mut Api, matches: &ArgMatches) -> MainResult<BuildTemplate> {
    let link = matches.value_of("chatlink").unwrap();
    Ok(BuildTemplate::from_chatlink(api, link)?)
}

/// Make sure a traitline is in the `"traitline:choice1:choice2:choice3"` format.
fn validate_traitline_format(input: String) -> Result<(), String> {
    let parts = input.split(':').collect::<Vec<_>>();
    if parts.len() != 4 {
        return Err("traitline format is line:trait_1:trait_2:trait_3".to_owned());
    }

    for part in parts.iter().skip(1) {
        let parsed = part.parse::<TraitChoice>();
        if parsed.is_err() {
            return Err(format!(
                "{} is not a valid trait. Use top, middle or bottom.",
                part
            ));
        }
    }

    Ok(())
}

/// Make sure a legend is valid.
fn validate_legend(input: String) -> Result<(), String> {
    input
        .parse::<Legend>()
        .map(|_| ())
        .map_err(|_| "invalid legend name".to_owned())
}

fn run() -> MainResult<()> {
    let matches = App::new(APP_NAME)
        .version("0.1")
        .author("Peter Parker IV")
        .about("Renders Guild Wars 2 skills and traits.")
        .arg(
            Arg::with_name("profession")
                .help("Selects which profession to use.")
                .required_unless("chatlink"),
        )
        .arg(
            Arg::with_name("skill")
                .help("Selects a skill based on either the name or the ID.")
                .takes_value(true)
                .number_of_values(1)
                .long("skill")
                .short("s")
                .multiple(true)
                .max_values(bt::SKILL_COUNT as u64),
        )
        .arg(
            Arg::with_name("traitline")
                .help("Selects a traitline.")
                .takes_value(true)
                .number_of_values(1)
                .long("traitline")
                .short("t")
                .multiple(true)
                .validator(validate_traitline_format)
                .max_values(bt::TRAITLINE_COUNT as u64),
        )
        .arg(
            Arg::with_name("legend")
                .help("Selects a revenant legend.")
                .takes_value(true)
                .number_of_values(1)
                .long("legend")
                .short("l")
                .multiple(true)
                .max_values(bt::LEGEND_COUNT as u64)
                .validator(validate_legend),
        )
        .arg(
            Arg::with_name("chatlink")
                .help("Specifies a chat link to parse.")
                .short("c")
                .long("chatlink")
                .takes_value(true)
                .conflicts_with_all(&["profession", "skill"]),
        )
        .arg(
            Arg::with_name("quiet")
                .help("Surpress console output except for the chat code.")
                .short("q")
                .long("quiet")
                .takes_value(false),
        )
        .arg(
            Arg::with_name("outfile")
                .help("Specifies the output filename")
                .short("o")
                .long("outfile")
                .default_value("buildtemplate.png")
                .takes_value(true),
        )
        .arg(
            Arg::with_name("no-cache")
                .help("Disables the cache")
                .long("no-cache")
                .takes_value(false),
        )
        .get_matches();

    let mut api = if matches.is_present("no-cache") {
        Api::new(cache::NoopCache::new())
    } else {
        Api::new(cache::FileCache::new())
    };
    let build = if matches.is_present("chatlink") {
        run_chatlink(&mut api, &matches)?
    } else {
        run_searching(&mut api, &matches)?
    };

    if !matches.is_present("quiet") {
        output::show_build_template(&build)?;
    } else {
        println!("{}", build.chatlink());
    }

    let mut renderer = render::Renderer::new(&mut api, Default::default());
    match renderer.render_buildtemplate(&build) {
        Ok(img) => {
            let filename = matches.value_of("outfile").unwrap();
            img.save(filename)?;
            if !matches.is_present("quiet") {
                println!("Image saved in {}", filename);
            }
        }
        Err(RenderError::EmptyBuild) => (),
        Err(err) => {
            eprintln!("Image could not be rendered:");
            output::show_error(&err)?;
        }
    }

    Ok(())
}

fn main() {
    let result = run();
    if let Err(e) = result {
        output::show_error(e.as_ref()).expect("Error while displaying error");
        std::process::exit(1);
    }
}