jelq

use std::fmt::Write as _;

use super::{meta, run::RunResource, runs};

use crate::game::{Branch, FORUM_THREAD, Run, SHOP};

pub const REL_BASE: &str = "https://jelq.dev/rels/";

/// One RFC 8288 link. `allow` and `lubricant` are extension attributes (§3), so a client never

/// has to guess what a target accepts.

struct Link<'a> {

    href: &'a str,

    rel: &'a str,

    allow: &'a str,

    title: Option<&'a str>,

    lubricant: Option<&'a str>,

}

impl Link<'_> {

    fn write(&self, out: &mut String) {

        if !out.is_empty() {

            out.push_str(", ");

        }

        let _ = write!(out, "<{}>; rel=\"{REL_BASE}{}\"", self.href, self.rel);

        if let Some(title) = self.title {

            let _ = write!(out, "; title=\"{title}\"");

        }

        let _ = write!(out, "; allow=\"{}\"", self.allow);

        if let Some(rule) = self.lubricant {

            let _ = write!(out, "; lubricant=\"{rule}\"");

        }

    }

}

pub fn header(run: &Run) -> String {

    let reach = run.reach();

    let mut out = String::new();

    let resources: [(&str, &RunResource, bool); 15] = [

        ("", &runs::RUN, true),

        ("floor", &runs::FLOOR, true),

        ("length", &runs::LENGTH, true),

        ("foreskin", &runs::FORESKIN, reach.foreskin),

        ("inventory", &runs::INVENTORY, true),

        ("techniques", &runs::TECHNIQUES, true),

        ("drawer", &runs::DRAWER, reach.drawer),

        ("kitchen", &runs::KITCHEN, reach.kitchen),

        ("re-read", &runs::REREAD, reach.thread),

        ("grip", &runs::GRIP, true),

        ("shop", &runs::SHOP, reach.shop),

        ("portal", &runs::PORTAL, reach.portal),

        ("elder", &runs::ELDER, reach.elder),

        ("footage", &runs::FOOTAGE, reach.footage),

        ("diagnosis", &runs::DIAGNOSIS, reach.diagnosis),

    ];

    for (rel, target, _) in resources.iter().filter(|(_, _, relevant)| *relevant) {

        let href = if rel.is_empty() {

            run.path("")

        } else {

            run.path(&format!("/{rel}"))

        };

        Link {

            href: &href,

            rel: if rel.is_empty() { "run" } else { rel },

            allow: &target.resource.allow(run),

            title: None,

            lubricant: None,

        }

        .write(&mut out);

    }

    if reach.thread {

        Link {

            href: FORUM_THREAD,

            rel: "thread",

            allow: &meta::THREAD.allow_any(),

            title: None,

            lubricant: None,

        }

        .write(&mut out);

    }

    if reach.branch_pending {

        for (branch, title) in [

            (Branch::Forum, "Read the forum"),

            (Branch::CloseTab, "Close the tab"),

        ] {

            Link {

                href: &run.path(&format!("/branches/{}", branch.slug())),

                rel: "branch",

                allow: "POST",

                title: Some(title),

                lubricant: None,

            }

            .write(&mut out);

        }

    }

    let run_path = run.path("");

    for technique in run.techniques_now() {

        let name = technique.name();

        Link {

            href: &format!("{run_path}?technique={name}"),

            rel: "technique",

            allow: "JELQ",

            title: Some(name),

            lubricant: technique.lubricant(),

        }

        .write(&mut out);

    }

    if reach.shopping {

        for item in SHOP {

            let Some(price) = run.price(item) else {

                continue;

            };

            Link {

                href: &run.path(&format!("/shop/{}", item.slug())),

                rel: "shop-item",

                allow: "POST",

                title: Some(&format!("{} for {price}", item.slug())),

                lubricant: None,

            }

            .write(&mut out);

        }

    }

    out

}