//! The rung ladder against the patches this tier actually ships.
//!
//! `src/patch.rs` proves the engine's rules on synthetic diffs, which is the right place to make a
//! rule fail on purpose. This file proves the same engine handles the three real ones — because
//! every property that matters here is a property of *those* files rather than of unified diffs in
//! general:
//!
//! - `commandlogging-event.patch` has no `diff --git` and no `index` line, so rung 1 is
//!   structurally unavailable for it and it must still apply through rung 2.
//! - `playervendor-sale-eventsink.patch` carries four hunks against one file, so the all-or-nothing
//!   rule, the descending-offset splice and the overlap check all get exercised at once.
//! - Every one of the three is CRLF in a Windows checkout and LF in the tarball CI builds, and both
//!   spellings have to behave identically.
//!
//! The fixtures are copies of `servuo-plugins/patches/*.patch`. The *targets* are synthesized
//! rather than vendored: the real ones are ServUO's own sources, and reproducing the region a hunk
//! expects — surrounded by filler that is deliberately not ServUO — is a stricter test of a
//! content match than pasting in 2,600 lines that happen to contain it.

use rgdeploy::diff;
use rgdeploy::patch::{self, Refusal, Resolution, Rung};
use rgdeploy::util::git_blob_hash;

const PATCHES: &[(&str, &str)] = &[
    ("commandlogging-event.patch", "Scripts/Commands/Logging.cs"),
    ("playervendor-sale-eventsink.patch", "Server/EventSink.cs"),
    (
        "playervendor-sale-gump.patch",
        "Scripts/Gumps/PlayerVendorGumps.cs",
    ),
];

fn fixture(name: &str) -> Vec<u8> {
    let path = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
        .join("tests")
        .join("fixtures")
        .join(name);
    std::fs::read(&path).unwrap_or_else(|e| panic!("cannot read {}: {e}", path.display()))
}

fn parse(name: &str) -> diff::FilePatch {
    diff::parse(&fixture(name))
        .unwrap_or_else(|e| panic!("{name} did not parse: {e}"))
        .single_file()
        .unwrap_or_else(|e| panic!("{name} is not single-target: {e}"))
        .clone()
}

/// A stand-in for the stock ServUO file: each hunk's pre-image, in order, separated by filler that
/// could not be mistaken for context.
fn synthesize_target(file: &diff::FilePatch, eol: &str) -> Vec<u8> {
    let mut out = String::new();
    for (i, hunk) in file.hunks.iter().enumerate() {
        for f in 0..12 {
            out.push_str(&format!("// unrelated shard code {i}/{f}{eol}"));
        }
        for line in hunk.pre_image() {
            out.push_str(&String::from_utf8_lossy(line));
            out.push_str(eol);
        }
    }
    out.push_str(&format!("// end of file{eol}"));
    out.into_bytes()
}

fn edits_of(resolution: &Resolution) -> &[patch::Edit] {
    match resolution {
        Resolution::Applicable { edits, .. } => edits,
        other => panic!("expected an applicable resolution, got {other:?}"),
    }
}

#[test]
fn every_shipped_patch_parses_and_names_its_declared_target() {
    for (name, target) in PATCHES {
        let file = parse(name);
        assert_eq!(&file.path, target, "{name}");
        assert!(!file.hunks.is_empty(), "{name}");
        assert!(
            file.hunks.iter().any(|h| !h.is_noop()),
            "{name} changes nothing"
        );
    }
}

#[test]
fn a_patch_without_an_index_line_still_applies_through_rung_two() {
    // commandlogging-event.patch is a plain ---/+++ diff. Rung 1 cannot be reached for it at all,
    // which must be a fact the tier reports rather than a reason to skip the patch.
    let file = parse("commandlogging-event.patch");
    assert_eq!(file.pre_blob, None, "this fixture has no index line");

    let target = synthesize_target(&file, "\r\n");
    let resolution = patch::resolve(&file, &target);
    assert_eq!(resolution.rung(), Some(Rung::RegionMatch));

    let patched = patch::apply(&target, edits_of(&resolution));
    let text = String::from_utf8(patched).unwrap();
    assert!(
        text.contains("public static event Action<Mobile, string> OnWrite;"),
        "{text}"
    );
    // The `m_Enabled` early return is deleted from the two-argument overload — a removal, not just
    // an insertion, so the splice is doing more than appending.
    assert_eq!(text.matches("if (!m_Enabled)").count(), 1, "{text}");
}

#[test]
fn the_four_hunk_patch_applies_all_of_them_at_the_right_offsets() {
    // EventSink.cs is the one with several hunks in one file: the descending-offset splice, the
    // overlap check and the all-or-nothing rule are all exercised together here.
    let file = parse("playervendor-sale-eventsink.patch");
    assert_eq!(file.hunks.len(), 4);

    let target = synthesize_target(&file, "\r\n");
    let resolution = patch::resolve(&file, &target);
    assert_eq!(resolution.rung(), Some(Rung::RegionMatch));
    assert_eq!(resolution.placements().len(), 4);

    // Every hunk landed somewhere different, and in the order the diff declares them.
    let lines: Vec<usize> = resolution
        .placements()
        .iter()
        .map(|p| p.matched_line)
        .collect();
    assert!(lines.windows(2).all(|w| w[0] < w[1]), "{lines:?}");

    let text = String::from_utf8(patch::apply(&target, edits_of(&resolution))).unwrap();
    for expected in [
        "public delegate void PlayerVendorSaleEventHandler(PlayerVendorSaleEventArgs e);",
        "public class PlayerVendorSaleEventArgs : EventArgs",
        "public static event PlayerVendorSaleEventHandler PlayerVendorSale;",
        "public static void InvokePlayerVendorSale(PlayerVendorSaleEventArgs e)",
    ] {
        assert!(text.contains(expected), "missing: {expected}");
    }
}

#[test]
fn a_stock_target_reaches_rung_one() {
    // The synthesized file is not ServUO's, so its blob hash is not the one the diff records. Feed
    // the diff the hash of the file it is about to be resolved against, which is exactly the
    // situation on a genuinely stock tree.
    for (name, _) in PATCHES {
        let file = parse(name);
        let target = synthesize_target(&file, "\r\n");
        let stated = diff::FilePatch {
            pre_blob: Some(git_blob_hash(&target)[..7].to_string()),
            ..file
        };
        assert_eq!(
            patch::resolve(&stated, &target).rung(),
            Some(Rung::StockHash),
            "{name}"
        );
    }
}

#[test]
fn applying_twice_is_a_no_op_for_every_shipped_patch() {
    // The idempotence promise: `install` is documented as safe to re-run, and the tier is the part
    // of it that edits files the operator owns.
    for (name, _) in PATCHES {
        let file = parse(name);
        let target = synthesize_target(&file, "\r\n");

        let first = patch::apply(&target, edits_of(&patch::resolve(&file, &target)));
        let second = patch::resolve(&file, &first);
        assert_eq!(second.rung(), Some(Rung::AlreadyPresent), "{name}");
        assert!(
            matches!(second, Resolution::AlreadyPresent { .. }),
            "{name} would be applied a second time"
        );
    }
}

#[test]
fn an_edit_inside_a_patched_region_is_refused_for_every_shipped_patch() {
    // Rung 3 is the outcome most real shards will see on at least one patch, so it must be the one
    // that never writes. The edit is placed on the first line the hunk actually removes or keeps.
    for (name, _) in PATCHES {
        let file = parse(name);
        let target = synthesize_target(&file, "\n");

        let anchor = file.hunks[0]
            .pre_image()
            .iter()
            .map(|l| String::from_utf8_lossy(l).to_string())
            .find(|l| l.trim().len() > 12)
            .expect("a substantial context line to vandalize");
        let vandalized = String::from_utf8_lossy(&target)
            .replacen(&anchor, &format!("{anchor} /* operator's own change */"), 1)
            .into_bytes();
        assert_ne!(vandalized, target, "{name}: the fixture was not modified");

        match patch::resolve(&file, &vandalized) {
            Resolution::Refused(Refusal::RegionModified { .. }) => {}
            other => panic!("{name}: expected a refusal, got {other:?}"),
        }
    }
}

#[test]
fn line_endings_do_not_change_the_verdict_or_the_result() {
    // A patch is CRLF in a Windows checkout and LF in the tarball, and a target may be either. The
    // rung reached must not depend on that, and the patched file must keep the ending it had.
    for (name, _) in PATCHES {
        let raw = fixture(name);
        let as_lf = String::from_utf8_lossy(&raw)
            .replace("\r\n", "\n")
            .into_bytes();
        let as_crlf = String::from_utf8_lossy(&as_lf)
            .replace('\n', "\r\n")
            .into_bytes();

        let from_lf = diff::parse(&as_lf).unwrap().single_file().unwrap().clone();
        let from_crlf = diff::parse(&as_crlf)
            .unwrap()
            .single_file()
            .unwrap()
            .clone();
        assert_eq!(
            from_lf, from_crlf,
            "{name}: the two spellings parsed differently"
        );

        for eol in ["\n", "\r\n"] {
            let target = synthesize_target(&from_lf, eol);
            let resolution = patch::resolve(&from_lf, &target);
            assert_eq!(resolution.rung(), Some(Rung::RegionMatch), "{name} {eol:?}");

            let patched = patch::apply(&target, edits_of(&resolution));
            let newlines = patched.iter().filter(|b| **b == b'\n').count();
            let crlfs = patched.windows(2).filter(|w| w == b"\r\n").count();
            if eol == "\r\n" {
                assert_eq!(crlfs, newlines, "{name}: LF islands in a CRLF file");
            } else {
                assert_eq!(crlfs, 0, "{name}: CR appeared in an LF file");
            }
        }
    }
}

#[test]
fn the_tier_the_release_workflow_emits_is_the_one_this_installer_reads() {
    // `patch_tier.json` is the literal output of the jq filter in
    // servuo-plugins/.gitea/workflows/release.yml, run over that repo's patches/tier.json. It is
    // checked in so the two repos cannot drift apart quietly: a renamed field there would fail
    // here rather than producing an empty tier on an operator's shard, where the only symptom is
    // a patch tier that is never offered.
    let json = std::fs::read_to_string(
        std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
            .join("tests")
            .join("fixtures")
            .join("patch_tier.json"),
    )
    .unwrap();

    // Deserialized through Manifest, not through Tier, because the field's name and its
    // `Option`-ness are half of the contract.
    let manifest: serde_json::Value = serde_json::json!({
        "component": "servuo-plugins-overlay",
        "version": "0.2.0",
        "commit": "0000000",
        "repo": "RunicGateway/servuo-plugins",
        "protocol": 3,
        "servuo": { "min_version": "57.4", "patches_verified_against": "57.4" },
        "patch_tier": serde_json::from_str::<serde_json::Value>(&json).unwrap(),
        "files": {}
    });
    let manifest: rgdeploy::overlay::Manifest = serde_json::from_value(manifest).unwrap();
    let declared = manifest.patch_tier.expect("patch_tier must deserialize");

    // The declared tier and the built-in fallback have to describe the same release, or an
    // installer would behave differently against v0.1.1 and v0.2.0 of the same overlay.
    assert_eq!(declared, rgdeploy::patch::Tier::builtin());

    // ...and everything it names must be resolvable against the patches that ship.
    for feature in &declared.features {
        for declared_patch in &feature.patches {
            let file = parse(&declared_patch.file.replace("patches/", ""));
            assert_eq!(file.path, declared_patch.target, "{}", declared_patch.name);
        }
        for companion in &feature.companions {
            assert!(companion.file.starts_with("patches/"), "{companion:?}");
        }
    }
}

#[test]
fn the_builtin_tier_names_exactly_the_patches_that_ship() {
    // The fallback for overlay releases older than `patch_tier` in the manifest. It has to describe
    // the release it stands in for, and the fixtures here are that release's patches.
    let tier = rgdeploy::patch::Tier::resolve(None);
    let mut declared: Vec<String> = tier
        .features
        .iter()
        .flat_map(|f| f.patches.iter())
        .map(|p| p.file.replace("patches/", ""))
        .collect();
    declared.sort();

    let mut shipped: Vec<String> = PATCHES.iter().map(|(n, _)| n.to_string()).collect();
    shipped.sort();
    assert_eq!(declared, shipped);

    for feature in &tier.features {
        for declared in &feature.patches {
            let file = parse(&declared.file.replace("patches/", ""));
            assert_eq!(
                file.path, declared.target,
                "{}: the fallback declares a target the diff does not edit",
                declared.name
            );
        }
    }
}