//! Reference vectors pinning every verification state (PLAN.md step 3).
//!
//! Cases are built from fixed seeds; Ed25519 signing is deterministic, so a
//! rebuilt case is byte-identical to `vectors.json`. The regular tests pin
//! both directions — the JSON must verify to its recorded states, and the
//! code must regenerate exactly the JSON's feeds. `write_vectors`
//! regenerates the file after an intentional format change:
//! `cargo test -- --ignored write_vectors`.

use fumi_core::account::{identity_seed, Identity};
use fumi_core::crypto::b32;
use smolboid_core::feed::{Feed, MailLine};
use smolboid_core::verify::{reply_to_body, repost_body, signed_bytes, verify, State};
use smolboid_core::time;

/// Distinct fixed masters: 0xA0/0xA1 are the daemon's identity keys across a
/// rotation, 0xB0 a foreign instance, 0x5B the author.
const HOST0: u8 = 0xA0;
const HOST1: u8 = 0xA1;
const FOREIGN: u8 = 0xB0;
const AUTHOR: u8 = 0x5B;
const EPK: [u8; 32] = [0xE7; 32];

fn identity(master: u8, index: u32) -> Identity {
    Identity::from_seed(identity_seed(&[master; 32], index))
}

/// Signs a record the way smolmail seals it, so the feed carries the very
/// signature that sealed the mail (PLAN.md, Signing).
fn sign(sender: &Identity, to: [u8; 32], unix: i64, body: &str) -> MailLine {
    let sender_pk = sender.pk();
    MailLine {
        sender: sender_pk,
        epk: EPK,
        sig: sender.sign(&signed_bytes(&to, &EPK, &sender_pk, unix, body.as_bytes())),
    }
}

fn post(sender: &Identity, to: [u8; 32], unix: i64, text: &str) -> String {
    let mail = sign(sender, to, unix, text);
    // The bare form of a post.
    format!(
        "{}\t{}\n{}\n",
        time::render(unix),
        text,
        mail.render()
    )
}

fn post_with_reply_to(sender: &Identity, to: [u8; 32], unix: i64, reply_to: &str, text: &str) -> String {
    let mail = sign(sender, to, unix, &reply_to_body(reply_to, text));
    format!(
        "{}\t{}\n{}\n",
        time::render(unix),
        text,
        mail.render()
    )
}

fn repost(sender: &Identity, to: [u8; 32], unix: i64, args: &str) -> String {
    let mail = sign(sender, to, unix, &repost_body(args, None));
    format!(
        "# smol:repost {} {}\n{}\n",
        time::render(unix),
        args,
        mail.render()
    )
}

fn repost_with_reply_to(sender: &Identity, to: [u8; 32], unix: i64, reply_to: &str, args: &str) -> String {
    let mail = sign(sender, to, unix, &repost_body(args, Some(reply_to)));
    format!(
        "# smol:repost {} {}\n{}\n",
        time::render(unix),
        args,
        mail.render()
    )
}

struct Case {
    name: &'static str,
    feed: String,
    legacy: bool,
    states: Vec<State>,
}

fn metadata(host_keys: &[[u8; 32]]) -> String {
    let mut meta = String::from(
        "# nick = tobias\n# url = https://smol.place/twtxt/tobias.txt\n# smol:author = tobias@smol.place\n",
    );
    for key in host_keys {
        meta.push_str(&format!("# smol:host_key = {}\n", b32(key)));
    }
    meta
}



fn cases() -> Vec<Case> {
    let host0 = identity(HOST0, 0).pk();
    let host1 = identity(HOST1, 0).pk();
    let foreign = identity(FOREIGN, 0).pk();
    let author = identity(AUTHOR, 0);
    let rotated = identity(AUTHOR, 1);
    let t1: i64 = 1_760_000_000;
    let t2 = t1 + 3600;
    let t3 = t2 + 3600;

    let meta1 = metadata(&[host0]);

    vec![
        Case {
            name: "verified_post",
            feed: format!("{}{}", meta1, post(&author, host0, t1, "hello smolverse")),
            legacy: false,
            states: vec![State::Verified],
        },
        Case {
            name: "unsigned_post",
            feed: format!(
                "{}{}\t{}\n",
                meta1,
                time::render(t1),
                "no signature line"
            ),
            legacy: false,
            states: vec![State::Unsigned],
        },
        Case {
            name: "invalid_tampered_text",
            // Signed over "hello smolverse", published as "hello sm0lverse".
            feed: format!(
                "{}{}\t{}\n{}\n",
                meta1,
                time::render(t1),
                "hello sm0lverse",
                sign(&author, host0, t1, "hello smolverse").render()
            ),
            legacy: false,
            states: vec![State::Invalid],
        },
        Case {
            name: "invalid_foreign_host",
            // Sealed to another instance: no host_key matches, so the record
            // cannot be laundered into this feed.
            feed: format!(
                "{}{}",
                meta1,
                post(&author, foreign, t1, "sealed elsewhere")
            ),
            legacy: false,
            states: vec![State::Invalid],
        },
        Case {
            name: "invalid_bad_timestamp",
            feed: format!(
                "{}{}\t{}\n{}\n",
                meta1,
                "2026-13-40T99:99:99Z",
                "unparseable time",
                sign(&author, host0, t1, "unparseable time").render()
            ),
            legacy: false,
            states: vec![State::Invalid],
        },
        Case {
            name: "legacy_feed",
            // No smol:author and no host_key: plain twtxt, records not judged.
            feed: format!(
                "# nick = tobias\n{}\t{}\n",
                time::render(t1),
                "just a legacy twt"
            ),
            legacy: true,
            states: vec![State::Unsigned],
        },
        Case {
            name: "orphan_mail_line",
            feed: format!(
                "{}{}{}",
                meta1,
                post(&author, host0, t1, "with a signature"),
                format!(
                    "# smol:mail {} {} {}\n",
                    b32(&author.pk()),
                    b32(&EPK),
                    b32(&author.sign(&signed_bytes(
                        &host0,
                        &EPK,
                        &author.pk(),
                        t2,
                        "orphaned".as_bytes()
                    )))
                )
            ),
            legacy: false,
            // The second mail line belongs to no record and is ignored.
            states: vec![State::Verified],
        },
        Case {
            name: "host_rotation",
            // Both eras verify because each host_key is tried in turn.
            feed: format!(
                "{}{}{}",
                metadata(&[host0, host1]),
                post(&author, host0, t1, "before the rotation"),
                post(&author, host1, t2, "after the rotation")
            ),
            legacy: false,
            states: vec![State::Verified, State::Verified],
        },
        Case {
            name: "author_rotation",
            // Per-record sender keys: old posts stay valid under the old key.
            feed: format!(
                "{}{}{}",
                meta1,
                post(&author, host0, t1, "identity index 0"),
                post(&rotated, host0, t2, "identity index 1")
            ),
            legacy: false,
            states: vec![State::Verified, State::Verified],
        },
        Case {
            name: "verified_repost",
            feed: format!(
                "{}{}",
                meta1,
                repost(
                    &author,
                    host0,
                    t1,
                    "@<dana https://smol.place/twtxt/dana.txt> #abc1234"
                )
            ),
            legacy: false,
            states: vec![State::Verified],
        },
        Case {
            name: "invalid_repost_tampered",
            feed: format!(
                "{}{}",
                meta1,
                repost(
                    &author,
                    host0,
                    t1,
                    "@<dana https://smol.place/twtxt/dana.txt> #abc1234"
                )
                .replace("#abc1234", "#fedcba9") // signed over #abc1234
            ),
            legacy: false,
            states: vec![State::Invalid],
        },
        Case {
            name: "dashed_post",
            // Text beginning with `---` is sent raw: a single line can never
            // open a §5.5 frontmatter block, so nothing is escaped.
            feed: format!(
                "{}{}",
                meta1,
                post(&author, host0, t1, "--- dashed opening")
            ),
            legacy: false,
            states: vec![State::Verified],
        },
        Case {
            name: "reply_to_post",
            // An ordinary send carries a signed Reply-To block; the verifier
            // derives the same value from the author address and sender key.
            feed: format!(
                "{}{}",
                meta1,
                post_with_reply_to(
                    &author,
                    host0,
                    t1,
                    &format!("smol://tobias@smol.place/{}", b32(&author.pk())),
                    "hello from an ordinary send"
                )
            ),
            legacy: false,
            states: vec![State::Verified],
        },
        Case {
            name: "reply_to_key_mismatch_is_forged",
            // The signature covers a Reply-To naming a different key than
            // the record's sender, so no derived form reconstructs.
            feed: format!(
                "{}{}",
                meta1,
                post_with_reply_to(
                    &author,
                    host0,
                    t1,
                    &format!("smol://tobias@smol.place/{}", b32(&[0xEE; 32])),
                    "signed with a foreign reply-to"
                )
            ),
            legacy: false,
            states: vec![State::Invalid],
        },
        Case {
            name: "repost_with_reply_to",
            feed: format!(
                "{}{}",
                meta1,
                repost_with_reply_to(
                    &author,
                    host0,
                    t1,
                    &format!("smol://tobias@smol.place/{}", b32(&author.pk())),
                    "@<dana https://smol.place/twtxt/dana.txt> #abc1234"
                )
            ),
            legacy: false,
            states: vec![State::Verified],
        },
        Case {
            name: "mixed_feed",
            feed: format!(
                "{}{}\t{}\n{}{}{}",
                meta1,
                time::render(t1),
                "unsigned legacy line",
                post(&author, host0, t2, "signed after it"),
                repost(&author, host0, t3, "@<nick url> #hash123"),
                post(&author, foreign, t1 + 7200, "signed to a foreign host")
            ),
            legacy: false,
            states: vec![
                State::Unsigned,
                State::Verified,
                State::Verified,
                State::Invalid,
            ],
        },
    ]
}

#[test]
fn cases_verify_to_their_expected_states() {
    for case in cases() {
        let report = verify(&Feed::parse(&case.feed));
        assert_eq!(report.legacy, case.legacy, "{}: legacy flag", case.name);
        assert_eq!(report.states, case.states, "{}: states", case.name);
    }
}

#[test]
fn parse_render_round_trips_every_case() {
    for case in cases() {
        assert_eq!(Feed::parse(&case.feed).render(), case.feed, "{}", case.name);
    }
}

#[test]
fn vectors_json_pins_the_generated_cases() {
    let path = concat!(env!("CARGO_MANIFEST_DIR"), "/vectors.json");
    let pinned: serde_json::Value =
        serde_json::from_str(&std::fs::read_to_string(path).expect("vectors.json present"))
            .expect("vectors.json parses");
    let pinned_cases = pinned["cases"].as_array().expect("cases array");
    let generated = cases();
    assert_eq!(
        pinned_cases.len(),
        generated.len(),
        "vectors.json and the code disagree on the case set"
    );

    for (pinned, case) in pinned_cases.iter().zip(&generated) {
        assert_eq!(pinned["name"], case.name, "case order");
        assert_eq!(pinned["feed"], case.feed, "{}: feed bytes", case.name);
        assert_eq!(pinned["legacy"], case.legacy, "{}: legacy", case.name);
        let states: Vec<&str> = pinned["states"]
            .as_array()
            .unwrap()
            .iter()
            .map(|s| s.as_str().unwrap())
            .collect();
        let expected: Vec<&str> = case.states.iter().map(State::as_str).collect();
        assert_eq!(states, expected, "{}: states", case.name);

        // The pinned feed must verify exactly as recorded.
        let report = verify(&Feed::parse(case.feed.as_str()));
        assert_eq!(report.legacy, case.legacy);
        assert_eq!(
            report
                .states
                .iter()
                .map(State::as_str)
                .collect::<Vec<_>>(),
            states
        );
    }
}

#[test]
#[ignore = "regenerates core/vectors.json after an intentional format change"]
fn write_vectors() {
    let cases: Vec<serde_json::Value> = cases()
        .iter()
        .map(|case| {
            serde_json::json!({
                "name": case.name,
                "feed": case.feed,
                "legacy": case.legacy,
                "states": case.states.iter().map(State::as_str).collect::<Vec<_>>(),
            })
        })
        .collect();
    let doc = serde_json::json!({
        "comment": "smolboid-core verification vectors; regenerate with: cargo test -- --ignored write_vectors",
        "cases": cases,
    });
    let path = concat!(env!("CARGO_MANIFEST_DIR"), "/vectors.json");
    std::fs::write(path, serde_json::to_string_pretty(&doc).unwrap() + "\n").unwrap();
}