use std::{
    fmt::Write,
    path::PathBuf,
    sync::{Arc, RwLock},
};

use anyhow::Result;
use axum::{
    extract::{Path, State},
    http::StatusCode,
    response::{IntoResponse, Redirect, Response},
    routing::get,
    Form, Router,
};
use chrono::prelude::*;
use common::{footer, head, header, style};
use maud::{html, Escaper, Markup, PreEscaped};
use serde::{Deserialize, Serialize};
use store::Store;
use tokio::net::TcpListener;
use validator::{Validate, ValidationError};

mod common;
mod store;

#[derive(Debug, clap::Parser)]
/// Arbre
struct Cmd {
    #[arg(short, long, default_value_t = 8200)]
    /// Port on which th server will listen.
    port: u16,

    #[arg(short, long, default_value = "0.0.0.0")]
    /// Hostname or address on which th server will listen.
    address: String,

    #[arg(short, long, default_value = "./store")]
    /// Path to the directory to use as storage for topics.
    store: PathBuf,
}

#[derive(Debug, Clone)]
struct MainState {
    store: Arc<RwLock<Store>>,
}

#[tokio::main]
async fn main() -> Result<()> {
    let Cmd {
        address,
        port,
        store,
    } = clap::Parser::parse();

    let store = Store::open(store)?;
    let store = Arc::new(RwLock::new(store));
    let state = MainState { store };

    let app = Router::new()
        .route("/style.css", get(style))
        .route("/topics", get(topics).post(post))
        .route("/topic/:name", get(topic))
        .route("/create", get(create))
        .route("/activity", get(activity))
        .route("/", get(home))
        .with_state(state);

    let listener = TcpListener::bind((address, port)).await.unwrap();
    let server = axum::serve(listener, app);
    server.await?;

    Ok(())
}

async fn home() -> Markup {
    html!(
        (head(""))
        body {
            content {
                (header())
                main {
                    "Bienvenue au recueil de Barnulf."
                    br;
                    "
                    Ce site contient une collection ouverte de réflexions
                    personnelles sur différents sujets relatifs à l'informatique.
                    "
                }
                (footer())
            }
        }
    )
}

async fn topics(State(state): State<MainState>) -> impl IntoResponse {
    let topics = state.store.read().unwrap().list().unwrap();
    html!(
        (head("sujets"))
        body {
            content {
                (header())
                main {
                    h2 { "Sujets" }
                    ul {
                        @for topic in topics {
                            li {
                                a href = { "/topic/" (topic) } { (topic) }
                            }
                        }
                    }
                }
                (footer())
            }
        }
    )
}

async fn activity(State(state): State<MainState>) -> impl IntoResponse {
    let topics = state.store.read().unwrap().activity().unwrap();
    html!(
        (head("activité"))
        body {
            content {
                (header())
                main {
                    h2 { "Activité" }
                    ul {
                        @for topic in topics {
                            li {
                                a href = { "/topic/" (topic) } { (topic) }
                            }
                        }
                    }
                }
                (footer())
            }
        }
    )
}

async fn topic(Path(name): Path<String>, State(state): State<MainState>) -> impl IntoResponse {
    let Ok(posts) = state.store.read().unwrap().get(&name) else {
        return error("No such topic.");
    };

    html!(
        (head(&name))
        body {
            content {
                (header())
                main {
                    h2 { (name) }

                    @for post in posts {
                        hr;
                        section { (PreEscaped({
                            let mut buffer = String::new();
                            write!(Escaper::new(&mut buffer), "{post}").unwrap();
                            buffer.replace('\n', "<br>")
                        })) }
                    }
                }
                (footer())
            }
        }
    )
}

#[derive(Debug, Clone, Serialize, Deserialize, Validate)]
struct PostContent {
    #[validate(length(min = 1, max = 32), custom(function = "validate_topic"))]
    topic: String,
    #[validate(length(min = 10, max = 10_000))]
    content: String,
    #[validate(length(min = 2, max = 32))]
    author: String,
}

fn validate_topic(topic: &str) -> Result<(), ValidationError> {
    if topic.starts_with('_') || topic.ends_with('_') {
        return Err(ValidationError::new("Bad topic format."));
    }
    Ok(())
}

async fn post(State(state): State<MainState>, Form(post_content): Form<PostContent>) -> Response {
    let mut store = state.store.write().unwrap();
    let date = Utc::now().format("%d/%m/%Y");

    if post_content.validate().is_err() {
        return (StatusCode::BAD_REQUEST, "Bad input.").into_response();
    }

    let PostContent {
        topic,
        content,
        author,
    } = post_content;

    let topic = sanithize_identifier(&topic);

    let content = format!("{content}\n\t~{author}, {date}");
    store.insert(&topic, content).unwrap();
    Redirect::to("/activity").into_response()
}

fn sanithize_identifier(input: &str) -> String {
    let text = input.to_lowercase();
    let replaces = [
        ('à', 'a'),
        ('â', 'a'),
        ('ä', 'a'),
        ('é', 'e'),
        ('è', 'e'),
        ('ê', 'e'),
        ('ë', 'e'),
        ('î', 'i'),
        ('ï', 'i'),
        ('ô', 'o'),
        ('ö', 'o'),
        ('û', 'u'),
        ('ü', 'u'),
        (' ', '_'),
    ];
    text.chars()
        .map(|c| {
            for (from, to) in replaces {
                if c == from {
                    return to;
                }
            }
            c
        })
        .filter(|c| c.is_ascii_lowercase() || *c == '_')
        .collect()
}

async fn create() -> impl IntoResponse {
    html!(
        (head("créer"))
        body {
            content {
                (header())
                main {
                    h2 { "Créer" }

                    form id = "create" action = "/topics" method = "post" {
                        label for = "topic" { "Sujet" }
                        input type = "text" name = "topic";
                        br;

                        label for = "author" { "Auteur" }
                        input type = "text" name = "author";
                        br;

                        label for = "content" { "Contenu" }
                        textarea form = "create" name = "content" {  }
                        br;

                        input type = "submit";
                    }
                }
                (footer())
            }
        }
    )
}

fn error(message: impl ToString) -> Markup {
    let message = message.to_string();
    html!(
        (head("Failure"))
        body {
            content {
                (header())
                main {
                    h2 { "Failure" }
                    br;
                    (message)
                }
                (footer())
            }
        }
    )
}