//! Shared presentation helpers.

use super::ui;

use anyhow::Result;

use oxy_core::hash::{ChangeHash, KeyId};

use oxy_core::objects::Change;

use oxy_core::repo::{Repo, SignatureStatus};

use oxy_core::state::ChangeMeta;

pub fn short_id(c: &Change) -> String {

    c.change_id.short(8)

}

/// `n head` / `n heads`.

pub fn plural(n: usize, word: &str) -> String {

    format!("{n} {word}{}", if n == 1 { "" } else { "s" })

}

/// Milliseconds since the Unix epoch as `YYYY-MM-DD HH:MM:SSZ`.

pub fn when(ms: u64) -> String {

    let secs = (ms / 1000) as i64;

    let days = secs.div_euclid(86_400);

    let rem = secs.rem_euclid(86_400);

    // Civil-from-days (Howard Hinnant), UTC.

    let z = days + 719_468;

    let era = z.div_euclid(146_097);

    let doe = z - era * 146_097;

    let yoe = (doe - doe / 1460 + doe / 36_524 - doe / 146_096) / 365;

    let y = yoe + era * 400;

    let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);

    let mp = (5 * doy + 2) / 153;

    let d = doy - (153 * mp + 2) / 5 + 1;

    let m = if mp < 10 { mp + 3 } else { mp - 9 };

    let y = if m <= 2 { y + 1 } else { y };

    format!(

        "{y:04}-{m:02}-{d:02} {:02}:{:02}:{:02}Z",

        rem / 3600,

        (rem % 3600) / 60,

        rem % 60

    )

}

/// One line describing how a change is authenticated.

pub fn signature_line(repo: &Repo, h: &ChangeHash) -> Result<String> {

    Ok(match repo.authenticate_change(h)? {

        SignatureStatus::Unsigned => "unsigned".to_string(),

        SignatureStatus::Valid {

            key,

            name,

            email,

            sealed,

            revoked,

        } => {

            format!(

                "{} by {name} <{email}> key {}{}",

                if sealed { "sealed" } else { "signed" },

                key.short(12),

                if revoked { " (KEY REVOKED)" } else { "" }

            )

        }

        SignatureStatus::Invalid(why) => format!("INVALID signature: {why}"),

    })

}

/// Who signed for the author when it was not the author: a delegate such

/// as an agent (`author.signer`), with the delegation that let it.

#[derive(Clone, Debug)]

pub struct Via {

    pub name: String,

    pub email: String,

    pub key: KeyId,

    /// The delegation as the author's identity lists it, if it still does.

    pub scope: Option<String>,

    pub expires: Option<u64>,

    pub revoked: bool,

}

impl Via {

    /// `↳ Antigravity <[email protected]> · delegate for changes, until … · key 3195…`

    pub fn line(&self) -> String {

        let delegation = match (&self.scope, self.revoked) {

            (_, true) => ui::err("delegation revoked"),

            (Some(scope), false) => ui::dim(format!(

                "delegate for {scope}{}",

                self.expires

                    .map(|e| format!(", until {}", when(e)))

                    .unwrap_or_default()

            )),

            (None, false) => ui::warn("not a delegate of the author now"),

        };

        format!(

            "{} {} <{}> · {} · key {}",

            ui::glyph("↳", "->"),

            ui::author(&self.name),

            self.email,

            delegation,

            ui::hash(self.key.short(12))

        )

    }

}

/// The delegate that signed for `author`, when one did. `None` when the

/// author signed, or nothing valid did.

pub fn via(repo: &Repo, status: &SignatureStatus, author: &KeyId) -> Option<Via> {

    match status {

        SignatureStatus::Valid {

            key,

            name,

            email,

            revoked,

            ..

        } if !author.is_zero() && key != author => {

            let entry = repo

                .identity(author)

                .ok()

                .and_then(|a| a.delegate(key).copied());

            Some(Via {

                name: name.clone(),

                email: email.clone(),

                key: *key,

                scope: entry.map(|d| d.scope.to_string()),

                expires: entry.and_then(|d| d.expires),

                revoked: *revoked || entry.is_none(),

            })

        }

        _ => None,

    }

}

/// A compact, styled authentication marker for log lines, from a status

/// already in hand (the caller also reads who signed, see [`via`]).

pub fn signature_mark_of(status: &SignatureStatus) -> String {

    match status {

        SignatureStatus::Unsigned => ui::dim(format!("{} unsigned", ui::glyph("·", "-"))),

        SignatureStatus::Valid {

            sealed,

            revoked: true,

            ..

        } => ui::warn(format!(

            "{} {} (key revoked)",

            ui::glyph("⚠", "!"),

            if *sealed { "sealed" } else { "signed" }

        )),

        SignatureStatus::Valid { sealed, .. } => ui::ok(format!(

            "{} {}",

            ui::glyph("✔", "v"),

            if *sealed { "sealed" } else { "signed" }

        )),

        SignatureStatus::Invalid(why) => ui::err(format!("{} INVALID: {why}", ui::glyph("✖", "x"))),

    }

}

/// The author's display name: the identity's name, or a Git-Author trailer

/// for imported changes, or a shortened key.

pub fn author_name(repo: &Repo, c: &ChangeMeta) -> String {

    if !c.author.is_zero() {

        if let Ok(id) = repo.identity(&c.author) {

            return id.name;

        }

        return c.author.short(12);

    }

    c.message

        .lines()

        .rev()

        .find_map(|l| l.strip_prefix("Git-Author: "))

        .map(|a| a.split('<').next().unwrap_or(a).trim().to_string())

        .unwrap_or_else(|| "unknown".into())

}

/// The first line of a message, or a placeholder.

pub fn subject_of(message: &str) -> &str {

    match message.lines().next() {

        Some(l) if !l.trim().is_empty() => l,

        _ => "(no description)",

    }

}

pub fn deps_line(c: &Change) -> String {

    deps_of(&c.deps)

}

pub fn deps_of(deps: &[oxy_core::hash::ChangeHash]) -> String {

    deps.iter()

        .map(|d| format!("#{}", d.short(12)))

        .collect::<Vec<_>>()

        .join(" ")

}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn dates() {

        assert_eq!(when(0), "1970-01-01 00:00:00Z");

        assert_eq!(when(1_700_000_000_000), "2023-11-14 22:13:20Z");

        assert_eq!(plural(1, "head"), "1 head");

        assert_eq!(plural(2, "head"), "2 heads");

    }

}