//! The emitted document: HTML shell, inline SVG table, inline JavaScript.
//!
//! ADR-0007 Decision 1. Marginal AM-4a cost zero — this is string
//! formatting, and the browser draws it.
//!
//! ## What the JavaScript is allowed to be
//!
//! ADR-0007 Decision 5 bars it from constructing commands. [`SCRIPT`] is
//! therefore the whole of it, it is a constant, and it does one thing:
//! record which element the pointer went down on, which it came up on, and
//! POST the pair. It contains no game vocabulary — no action names, no
//! seats, no rules. If a rule ever needs to appear in it, the decision is
//! wrong and ADR-0007 says to revisit it rather than widen the control.

use std::fmt::Write as _;

use cb_kernel::PlayerId;
use games_ground::view::{GroundView, PlayerView, ProblemView, SelectionView};

use crate::input::action_id;

/// Escape for text and attribute contexts alike.
///
/// Everything interpolated into the document goes through this. Card
/// suits and seat numbers cannot currently carry a `<`, but "cannot
/// currently" is how injection bugs are written.
pub fn esc(s: &str) -> String {
    let mut out = String::with_capacity(s.len());
    for c in s.chars() {
        match c {
            '&' => out.push_str("&amp;"),
            '<' => out.push_str("&lt;"),
            '>' => out.push_str("&gt;"),
            '"' => out.push_str("&quot;"),
            '\'' => out.push_str("&#39;"),
            _ => out.push(c),
        }
    }
    out
}

fn seat_name(p: PlayerId) -> String {
    format!("P{}", p.0 + 1)
}

fn cards(list: &[games_ground::SolutionCard]) -> String {
    if list.is_empty() {
        return "none".to_string();
    }
    list.iter()
        .map(|c| format!("{:?}", c.suit))
        .collect::<Vec<_>>()
        .join(" ")
}

/// The only JavaScript in the project. See the module docs.
pub const SCRIPT: &str = r#"
(function () {
  var down = null;
  function key(e) {
    var n = e.target;
    while (n && !(n.getAttribute && n.getAttribute('data-drop'))) { n = n.parentNode; }
    return n ? n.getAttribute('data-drop') : null;
  }
  document.addEventListener('pointerdown', function (e) { down = key(e); });
  document.addEventListener('pointerup', function (e) {
    var up = key(e);
    if (!down || !up) {
      // CB-WP-0016 T02: refusing is right; refusing SILENTLY is what let a
      // broken drop target survive a human sitting in front of it. Report
      // the raw fact — which element the pointer took and where it let go.
      // This decides nothing: it names elements, not moves.
      document.getElementById('cb-status').textContent =
        down ? 'took ' + down + ', let go over nothing droppable'
             : 'nothing droppable under the pointer';
      down = null;
      return;
    }
    var body = 'down=' + encodeURIComponent(down) + '&up=' + encodeURIComponent(up);
    down = null;
    fetch(window.CB_ENDPOINT, {
      method: 'POST',
      headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      body: body
    }).then(function (r) { return r.text(); }).then(function (t) {
      document.getElementById('cb-status').textContent = t;
      if (t.indexOf('ok') === 0) { window.location.reload(); }
    });
  });
})();
"#;

const STYLE: &str = "
body{font:14px/1.5 ui-monospace,monospace;margin:1.5rem;background:#12141a;color:#dde}
h1,h2{font-size:1rem;margin:1.2rem 0 .4rem;color:#9cf}
.row{display:flex;flex-wrap:wrap;gap:.5rem;align-items:flex-start}
.card{border:1px solid #445;border-radius:6px;padding:.5rem .7rem;background:#1b1e26}
.card[data-viewer=true]{border-color:#9cf}
.act{cursor:grab;user-select:none;background:#243;border-color:#5a7}
.btn{cursor:pointer;background:#332a3a;border-color:#a7d}
.k{color:#89a}
#cb-status{margin-top:1rem;color:#fc9;min-height:1.2em}
svg{background:#1b1e26;border:1px solid #445;border-radius:6px}
";

fn problem_svg(out: &mut String, priority: u32, p: &ProblemView, x: i32) {
    let (label, sub, fill) = match p {
        ProblemView::FaceDown => ("face down".to_string(), String::new(), "#2a2f3a"),
        ProblemView::FaceUp {
            suit,
            value,
            denied,
            claimed_by,
            protected_this_round,
        } => {
            let mut sub = String::new();
            if *denied {
                sub.push_str("denied ");
            }
            if *protected_this_round {
                sub.push_str("protected ");
            }
            if let Some(c) = claimed_by {
                let _ = write!(sub, "claimed by {}", seat_name(*c));
            }
            (
                format!("{suit:?} {value}"),
                sub.trim_end().to_string(),
                "#26303a",
            )
        }
    };
    let _ = write!(
        out,
        "<g data-drop=\"problem-{priority}\"><rect x=\"{x}\" y=\"10\" width=\"120\" height=\"78\" rx=\"8\" \
         fill=\"{fill}\" stroke=\"#5a6b7a\"/>\
         <text x=\"{tx}\" y=\"36\" fill=\"#dde\" font-size=\"13\">{label}</text>\
         <text x=\"{tx}\" y=\"56\" fill=\"#89a\" font-size=\"11\">priority {priority}</text>\
         <text x=\"{tx}\" y=\"74\" fill=\"#fc9\" font-size=\"11\">{sub}</text></g>",
        x = x,
        tx = x + 10,
        label = esc(&label),
        sub = esc(&sub),
    );
}

/// The relationship graph — the one element every Rust 2D toolkit would
/// have left us to hand-roll, and the reason SVG earns its place here
/// rather than merely fitting the budget (CB-RES-0006 §5).
fn relations_svg(view: &GroundView) -> String {
    let n = view.players.len().max(1);
    let (cx, cy, r) = (200.0f64, 150.0f64, 110.0f64);
    let pos: Vec<(PlayerId, f64, f64)> = view
        .players
        .keys()
        .enumerate()
        .map(|(i, p)| {
            let a = std::f64::consts::TAU * (i as f64) / (n as f64) - std::f64::consts::FRAC_PI_2;
            (*p, cx + r * a.cos(), cy + r * a.sin())
        })
        .collect();
    let find = |p: PlayerId| {
        pos.iter()
            .find(|(q, _, _)| *q == p)
            .map(|(_, x, y)| (*x, *y))
    };

    let mut s = String::from(
        "<svg width=\"400\" height=\"300\" role=\"img\" aria-label=\"relationship graph\">",
    );
    for (pair, rel) in &view.relations {
        if let (Some((x1, y1)), Some((x2, y2))) = (find(pair.0), find(pair.1)) {
            let colour = match rel {
                games_ground::Relation::Bond => "#5c9",
                games_ground::Relation::Rivalry => "#c66",
            };
            let _ = write!(
                s,
                "<line x1=\"{x1:.0}\" y1=\"{y1:.0}\" x2=\"{x2:.0}\" y2=\"{y2:.0}\" \
                 stroke=\"{colour}\" stroke-width=\"2\"/>\
                 <text x=\"{mx:.0}\" y=\"{my:.0}\" fill=\"{colour}\" font-size=\"10\">{rel:?}</text>",
                mx = (x1 + x2) / 2.0,
                my = (y1 + y2) / 2.0 - 3.0,
            );
        }
    }
    for (p, x, y) in &pos {
        let is_viewer = view.viewer == Some(*p);
        let focus = view
            .focus
            .get(p)
            .map(|f| format!(" \u{2192}{}", seat_name(*f)));
        let _ = write!(
            s,
            "<g data-drop=\"seat-{raw}\"><circle cx=\"{x:.0}\" cy=\"{y:.0}\" r=\"26\" fill=\"#1b1e26\" \
             stroke=\"{stroke}\" stroke-width=\"2\"/>\
             <text x=\"{x:.0}\" y=\"{ty:.0}\" fill=\"#dde\" font-size=\"12\" \
             text-anchor=\"middle\">{name}</text>\
             <text x=\"{x:.0}\" y=\"{ty2:.0}\" fill=\"#89a\" font-size=\"10\" \
             text-anchor=\"middle\">{focus}</text></g>",
            raw = p.0,
            stroke = if is_viewer { "#9cf" } else { "#5a6b7a" },
            ty = y + 2.0,
            ty2 = y + 16.0,
            name = seat_name(*p),
            focus = esc(focus.as_deref().unwrap_or("")),
        );
    }
    s.push_str("</svg>");
    s
}

fn player_card(out: &mut String, id: PlayerId, p: &PlayerView, view: &GroundView) {
    let is_viewer = view.viewer == Some(id);
    let _ = write!(
        out,
        // CB-WP-0016 T01: the seat card is a drop target. It could not be
        // while drop keys were `id`s — the graph node had already taken
        // `seat-{n}` and ids must be unique, so the card the instruction
        // text points at silently had none.
        "<div class=\"card\" data-viewer=\"{is_viewer}\" data-drop=\"seat-{raw}\">\
         <b>{name}</b>{you}<br>",
        raw = id.0,
        name = seat_name(id),
        you = if is_viewer { " (you)" } else { "" },
    );
    let _ = write!(
        out,
        "<span class=\"k\">stress</span> {} <span class=\"k\">protect</span> {} \
         <span class=\"k\">darvo</span> {:?}<br>",
        p.stress, p.protection, p.darvo
    );
    let _ = write!(
        out,
        "<span data-drop=\"freedom-{raw}\" class=\"act\"><span class=\"k\">freedom</span> \
         {ready}{lifted}</span><br>",
        raw = id.0,
        ready = if p.freedom_ready { "READY" } else { "spent" },
        lifted = if p.freedom_gate_lifted {
            " gate lifted"
        } else {
            ""
        },
    );
    let blame = if p.blame_from.is_empty() {
        "none".to_string()
    } else {
        p.blame_from
            .iter()
            .map(|b| seat_name(*b))
            .collect::<Vec<_>>()
            .join(" ")
    };
    let _ = write!(
        out,
        "<span class=\"k\">blamed by</span> {}<br>",
        esc(&blame)
    );
    match &p.hand {
        Some(h) => {
            let _ = write!(
                out,
                "<span class=\"k\">hand</span> {} ({} cards)<br>",
                esc(&cards(h)),
                p.hand_size
            );
        }
        None => {
            let _ = write!(
                out,
                "<span class=\"k\">hand</span> {} card(s), hidden<br>",
                p.hand_size
            );
        }
    }
    if let Some(sel) = view.selections.get(&id) {
        let _ = write!(
            out,
            "<span class=\"k\">selected</span> {}<br>",
            match sel {
                SelectionView::Hidden => "face down".to_string(),
                SelectionView::Shown(s) => esc(&format!("{s:?}")),
            }
        );
    }
    if let Some(m) = view.ground_modes.get(&id) {
        let _ = write!(out, "<span class=\"k\">ground mode</span> {m:?}<br>");
    }
    if let Some(c) = view.ground_choices.get(&id) {
        let _ = write!(out, "<span class=\"k\">ground choice</span> {c:?}<br>");
    }
    if let Some(r) = view.support_responses.get(&id) {
        let _ = write!(out, "<span class=\"k\">support</span> {r:?}<br>");
    }
    if let Some(t) = view.darvo_targets.get(&id) {
        let _ = write!(out, "<span class=\"k\">darvo target</span> {t:?}<br>");
    }
    out.push_str("</div>");
}

/// Render the whole table as a standalone document.
///
/// `may_pass` adds the one affordance that is not a command: declining to
/// act where the driver allows it. Like every other element it carries an
/// id and nothing else — the page still reports only that the pointer went
/// down and up on `pass`.
///
/// `legal` is the list the aggregate offered; the buttons carry indices
/// into it and nothing else (ADR-0007 control 5). `endpoint` carries the
/// per-process token (control 1) — the page cannot mint one.
pub fn document(
    view: &GroundView,
    legal: &[games_ground::GroundCommand],
    endpoint: &str,
    seat: Option<PlayerId>,
    may_pass: bool,
) -> String {
    let mut s = String::with_capacity(8192);
    let _ = write!(
        s,
        "<!doctype html><html lang=\"en\"><head><meta charset=\"utf-8\">\
         <meta name=\"viewport\" content=\"width=device-width,initial-scale=1\">\
         <title>GROUND \u{2014} round {round}</title><style>{STYLE}</style></head><body>",
        round = view.round
    );

    let _ = write!(
        s,
        "<h1>GROUND \u{2014} round {round}, step {step:?}</h1>\
         <div><span class=\"k\">lead</span> {lead} \
         <span class=\"k\">scoring</span> {mode:?} \
         <span class=\"k\">viewing as</span> {who}</div>",
        round = view.round,
        step = view.step,
        lead = seat_name(view.lead),
        mode = view.mode,
        who = match view.viewer {
            Some(p) => format!("{} (their hand only)", seat_name(p)),
            None => "a spectator (no hands)".to_string(),
        },
    );

    s.push_str(
        "<h2>problems</h2><svg width=\"760\" height=\"100\" role=\"img\" aria-label=\"problems\">",
    );
    if view.problems.is_empty() {
        s.push_str(
            "<text x=\"12\" y=\"52\" fill=\"#89a\" font-size=\"12\">no problems in play</text>",
        );
    }
    for (i, (priority, p)) in view.problems.iter().enumerate() {
        problem_svg(&mut s, *priority, p, 10 + (i as i32) * 130);
    }
    s.push_str("</svg>");

    s.push_str("<h2>relationships</h2>");
    s.push_str(&relations_svg(view));

    s.push_str("<h2>seats</h2><div class=\"row\">");
    for (id, p) in &view.players {
        player_card(&mut s, *id, p, view);
    }
    s.push_str("</div>");

    let _ = write!(
        s,
        "<h2>solutions</h2><div><span class=\"k\">deck</span> {} remaining \
         <span class=\"k\">discard</span> {}</div>",
        view.solution_deck_len,
        esc(&cards(&view.solution_discard)),
    );

    if let Some(o) = &view.outcome {
        let personal = o
            .personal
            .iter()
            .map(|(p, v)| format!("{} {v:+}", seat_name(*p)))
            .collect::<Vec<_>>()
            .join(" ");
        let winners = if o.winners.is_empty() {
            "nobody".to_string()
        } else {
            o.winners
                .iter()
                .map(|w| seat_name(*w))
                .collect::<Vec<_>>()
                .join(" ")
        };
        let coalitions = if o.coalitions.is_empty() {
            "none".to_string()
        } else {
            o.coalitions
                .iter()
                .map(|c| format!("{c:?}"))
                .collect::<Vec<_>>()
                .join(" ")
        };
        let _ = write!(
            s,
            "<h2>outcome</h2><div class=\"card\">\
             <span class=\"k\">total</span> {total} of {threshold} \
             <span class=\"k\">group</span> {group}<br>\
             <span class=\"k\">personal</span> {personal}<br>\
             <span class=\"k\">coalitions</span> {coalitions}<br>\
             <span class=\"k\">mastery</span> {mastery}<br>\
             <span class=\"k\">winners</span> {winners}</div>",
            total = o.total,
            threshold = o.threshold,
            group = if o.group_success {
                "success"
            } else {
                "failure"
            },
            personal = esc(&personal),
            coalitions = esc(&coalitions),
            mastery = match o.mastery {
                Some(m) => format!("{m:+}"),
                None => "none".to_string(),
            },
            winners = esc(&winners),
        );
    }

    if !legal.is_empty() {
        s.push_str("<h2>your move</h2><div class=\"row\">");
        for a in [
            games_ground::Action::Investigate,
            games_ground::Action::Solve,
            games_ground::Action::Support,
            games_ground::Action::Attack,
            games_ground::Action::Ground,
        ] {
            let offered = seat.is_some_and(|seat| {
                legal.iter().any(|c| {
                    crate::input::affordance(c, seat).is_some_and(|(f, _)| f == action_id(a))
                })
            });
            if offered {
                let _ = write!(
                    s,
                    "<div class=\"card act\" data-drop=\"{id}\">drag {a:?} onto a seat, a problem, \
                     or the table</div>",
                    id = action_id(a),
                );
            }
        }
        s.push_str("</div><div class=\"row\">");
        for (i, c) in legal.iter().enumerate() {
            let spatial = seat.is_some_and(|seat| crate::input::affordance(c, seat).is_some());
            if !spatial {
                let _ = write!(
                    s,
                    "<div class=\"card btn\" data-drop=\"cmd-{i}\">{}</div>",
                    esc(&format!("{c:?}"))
                );
            }
        }
        s.push_str(
            "</div><div class=\"card\" data-drop=\"table\">the table \u{2014} drop here for an \
                    untargeted action</div>",
        );
    }
    if may_pass {
        s.push_str("<div class=\"card btn\" data-drop=\"pass\">pass \u{2014} decline to act</div>");
    }

    let _ = write!(
        s,
        "<div id=\"cb-status\">ready</div>\
         <script>window.CB_ENDPOINT={};</script><script>{SCRIPT}</script></body></html>",
        json_string(endpoint),
    );
    s
}

/// Quote a string as a JSON literal, so a token can never end the script.
fn json_string(s: &str) -> String {
    let mut out = String::with_capacity(s.len() + 2);
    out.push('"');
    for c in s.chars() {
        match c {
            '"' => out.push_str("\\\""),
            '\\' => out.push_str("\\\\"),
            '<' => out.push_str("\\u003c"),
            '>' => out.push_str("\\u003e"),
            '&' => out.push_str("\\u0026"),
            c if (c as u32) < 0x20 => {
                let _ = write!(out, "\\u{:04x}", c as u32);
            }
            c => out.push(c),
        }
    }
    out.push('"');
    out
}

/// Extract the document's visible text and element ids.
///
/// ADR-0007 control 6 requires the coverage gate to assert over the
/// **parsed emitted document**, not over the Rust that emits it. This is
/// that parse: it drops markup and returns what a reader would see, plus
/// the ids a pointer can address. A substring search over the raw source
/// would happily find a token inside a comment or a style rule.
/// Every `data-drop="…"` value in the document.
///
/// CB-WP-0016. A real parse of the attribute rather than a substring
/// search: `html.contains("seat-1")` would be satisfied by the *text*
/// "seat-1" and by `data-drop="seat-10"`, and the point of the check this
/// feeds is that an affordance can name a target that is not there.
///
/// **Drop keys are `data-drop`, not `id`, and that is the fix for
/// CB-WP-0016.** An `id` must be unique in a document, so exactly one
/// element could ever be `seat-0` — the relationship-graph circle took it
/// and the seat card the instruction text points at went without. A seat
/// is drawn twice and both drawings are the seat.
pub fn drop_keys(html: &str) -> std::collections::BTreeSet<String> {
    let mut out = std::collections::BTreeSet::new();
    let mut rest = html;
    while let Some(i) = rest.find("data-drop=\"") {
        let after = &rest[i + 11..];
        match after.find('"') {
            Some(j) => {
                out.insert(after[..j].to_string());
                rest = &after[j..];
            }
            None => break,
        }
    }
    out
}

pub fn text_of(html: &str) -> String {
    let mut out = String::with_capacity(html.len() / 2);
    let bytes: Vec<char> = html.chars().collect();
    let mut i = 0;
    let mut skip_to: Option<&str> = None;
    while i < bytes.len() {
        if bytes[i] == '<' {
            // Find the tag name.
            let start = i + 1;
            let mut j = start;
            while j < bytes.len() && bytes[j] != '>' {
                j += 1;
            }
            let tag: String = bytes[start..j.min(bytes.len())].iter().collect();
            let lower = tag.to_ascii_lowercase();
            let name = lower
                .trim_start_matches('/')
                .split([' ', '\t', '\n', '>'])
                .next()
                .unwrap_or("")
                .to_string();

            if let Some(want) = skip_to {
                if lower.starts_with('/') && name == want {
                    skip_to = None;
                }
            } else if name == "script" || name == "style" {
                // Their contents are not text a reader sees.
                if !lower.starts_with('/') && !lower.ends_with('/') {
                    skip_to = Some(if name == "script" { "script" } else { "style" });
                }
            } else {
                // Ids are addressable surface, so they count as rendered.
                if let Some(k) = lower.find("id=\"") {
                    let rest = &tag[k + 4..];
                    if let Some(end) = rest.find('"') {
                        out.push(' ');
                        out.push_str(&rest[..end]);
                    }
                }
            }
            i = j + 1;
            continue;
        }
        if skip_to.is_none() {
            out.push(bytes[i]);
        }
        i += 1;
    }
    // Unescape the entities esc() introduced, so a test looks for the text
    // a reader sees rather than its encoding.
    out.replace("&lt;", "<")
        .replace("&gt;", ">")
        .replace("&quot;", "\"")
        .replace("&#39;", "'")
        .replace("&amp;", "&")
}