vtcode-core 0.136.1

//! Patch tool facade that exposes Codex-compatible patch parsing and application.
//!
//! Actual patch parsing logic lives in `tools::editing::patch` so future edit
//! features can reuse the same primitives without depending on this facade.

use anyhow::Context;
use base64::Engine;
use base64::engine::general_purpose::STANDARD as BASE64;
use serde::{Deserialize, Serialize};
use serde_json::Value;
use std::path::PathBuf;

pub use crate::tools::editing::{Patch, PatchError, PatchHunk, PatchLine, PatchOperation};
pub use vtcode_utility_tool_specs::{
    APPLY_PATCH_ALIAS_DESCRIPTION, DEFAULT_APPLY_PATCH_INPUT_DESCRIPTION, SEMANTIC_ANCHOR_GUIDANCE,
    with_semantic_anchor_guidance,
};

/// Input structure for the apply_patch tool
#[derive(Debug, Deserialize, Serialize)]
pub struct ApplyPatchInput {
    pub input: String,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DecodedApplyPatchInput {
    pub text: String,
    pub source_bytes: usize,
    pub was_base64: bool,
}

pub fn patch_source_from_args(args: &Value) -> Option<&str> {
    let input = args.get("input").and_then(|value| value.as_str());
    let patch = args.get("patch").and_then(|value| value.as_str());

    // When only one alias field is present, use it (historical behavior).
    // When both are present, prefer the field whose content actually looks
    // like a VT Code patch. This prevents a non-patch `input` (e.g. raw file
    // contents emitted by some providers — see checkpoint turn_615) from
    // masking a valid `patch` field. Falls back to `input`-first precedence
    // only if neither field is patch-shaped.
    match (input, patch) {
        (Some(i), Some(p)) => {
            if crate::tools::editing::looks_like_vte_patch(p) && !crate::tools::editing::looks_like_vte_patch(i) {
                Some(p)
            } else {
                Some(i)
            }
        }
        (Some(i), None) => Some(i),
        (None, Some(p)) => Some(p),
        (None, None) => args.as_str(),
    }
}

pub fn decode_apply_patch_input(args: &Value) -> anyhow::Result<Option<DecodedApplyPatchInput>> {
    let Some(source) = patch_source_from_args(args) else {
        return Ok(None);
    };

    let was_base64 = source.starts_with("base64:");
    let cap = effective_max_payload_bytes();
    let text = if was_base64 {
        let decoded = BASE64.decode(&source[7..]).with_context(|| "Failed to decode base64 patch")?;
        enforce_decoded_size_limit(decoded.len(), source.len(), was_base64, cap)?;
        String::from_utf8(decoded).with_context(|| "Decoded patch is not valid UTF-8")?
    } else {
        enforce_decoded_size_limit(source.len(), source.len(), was_base64, cap)?;
        source.to_string()
    };

    Ok(Some(DecodedApplyPatchInput { text, source_bytes: source.len(), was_base64 }))
}

/// Extract filesystem paths affected by a mutating tool call.
///
/// Public `apply_patch` payloads are decoded and parsed through the same patch
/// grammar used for execution. Generic path-bearing mutation tools retain the
/// established singular and batch argument conventions. Tools whose payloads
/// do not expose paths return an empty vector and cannot invalidate a scoped
/// replay.
pub fn mutation_target_paths(tool_name: &str, args: &Value) -> Vec<PathBuf> {
    if crate::tools::names::canonical_tool_name(tool_name) == crate::config::constants::tools::APPLY_PATCH {
        return decode_apply_patch_input(args)
            .ok()
            .flatten()
            .and_then(|decoded| Patch::parse(&decoded.text).ok())
            .map(|patch| patch_mutation_target_paths(&patch))
            .unwrap_or_default();
    }

    const SINGULAR_KEYS: [&str; 7] = [
        "path",
        "file_path",
        "filepath",
        "target_path",
        "destination",
        "destination_path",
        "file",
    ];
    let Some(obj) = args.as_object() else {
        return Vec::new();
    };
    let mut paths = SINGULAR_KEYS
        .iter()
        .filter_map(|key| obj.get(*key).and_then(Value::as_str))
        .map(str::trim)
        .filter(|path| !path.is_empty())
        .map(PathBuf::from)
        .collect::<Vec<_>>();
    for key in ["items", "paths", "files"] {
        let Some(items) = obj.get(key).and_then(Value::as_array) else {
            continue;
        };
        for item in items {
            if let Some(path) = item.as_str().map(str::trim).filter(|path| !path.is_empty()) {
                paths.push(PathBuf::from(path));
            } else if let Some(item) = item.as_object() {
                paths.extend(SINGULAR_KEYS.iter().filter_map(|key| {
                    item.get(*key)
                        .and_then(Value::as_str)
                        .map(str::trim)
                        .filter(|path| !path.is_empty())
                        .map(PathBuf::from)
                }));
            }
        }
    }
    paths
}

/// Return every path mutated by an already-parsed patch.
///
/// Move operations include both their source and destination. The result is
/// sorted and deduplicated so execution metadata and replay invalidation share
/// one stable path set without parsing the patch payload a second time.
pub fn patch_mutation_target_paths(patch: &Patch) -> Vec<PathBuf> {
    let mut paths = patch
        .operations()
        .iter()
        .flat_map(|operation| match operation {
            PatchOperation::AddFile { path, .. } | PatchOperation::DeleteFile { path } => {
                vec![PathBuf::from(path)]
            }
            PatchOperation::UpdateFile { path, new_path, .. } => {
                let mut paths = vec![PathBuf::from(path)];
                paths.extend(new_path.as_deref().map(PathBuf::from));
                paths
            }
        })
        .collect::<Vec<_>>();
    paths.sort();
    paths.dedup();
    paths
}

fn enforce_decoded_size_limit(
    decoded_bytes: usize,
    source_bytes: usize,
    was_base64: bool,
    cap: usize,
) -> anyhow::Result<()> {
    // Cap applies to the *decoded* size to prevent base64 decompression-bomb-style attacks
    // where a small source expands to a very large patch.
    if decoded_bytes <= cap {
        return Ok(());
    }
    anyhow::bail!(
        "apply_patch payload too large after decoding: decoded={decoded_bytes} bytes (source={source_bytes} bytes, base64={was_base64}). \
         The per-patch cap is {cap} bytes; split the change into smaller patches or raise {UNIFIED_FILE_MAX_PAYLOAD_BYTES_ENV}."
    )
}

/// Hard upper bound for any single `apply_patch` payload after base64 decoding.
/// The preflight cap mirrors this same value; both share the same env-var override.
pub const UNIFIED_FILE_MAX_PAYLOAD_BYTES: usize = 1024 * 1024;

/// Maximum allowed decoded patch size — same as `UNIFIED_FILE_MAX_PAYLOAD_BYTES` but
/// exposed with a more specific name to clarify that it is enforced at decode time,
/// not preflight time.
pub const MAX_DECODED_PATCH_BYTES: usize = UNIFIED_FILE_MAX_PAYLOAD_BYTES;

/// Env var name that overrides both the preflight cap and the post-decode cap.
pub const UNIFIED_FILE_MAX_PAYLOAD_BYTES_ENV: &str = "VTCODE_UNIFIED_FILE_MAX_PAYLOAD_BYTES";

/// Resolve the effective cap, honoring the env-var override. A 1 KiB safety
/// floor is enforced so a sub-floor override can never silently disable the
/// post-decode cap; values below the floor fall back to the default. The same
/// floor is applied by the preflight resolver in `execution_kernel` so both
/// stages agree on the effective cap.
pub fn effective_max_payload_bytes() -> usize {
    std::env::var(UNIFIED_FILE_MAX_PAYLOAD_BYTES_ENV)
        .ok()
        .and_then(|v| v.trim().parse::<usize>().ok())
        .filter(|value| *value >= 1024)
        .unwrap_or(UNIFIED_FILE_MAX_PAYLOAD_BYTES)
}

pub fn parameter_schema(input_description: &str) -> Value {
    vtcode_utility_tool_specs::apply_patch_parameter_schema(input_description)
}

#[cfg(test)]
mod tests {
    use super::{
        APPLY_PATCH_ALIAS_DESCRIPTION, SEMANTIC_ANCHOR_GUIDANCE, decode_apply_patch_input, mutation_target_paths,
        parameter_schema, patch_mutation_target_paths, patch_source_from_args, with_semantic_anchor_guidance,
    };
    use serde_json::json;
    use std::path::PathBuf;

    #[test]
    fn patch_source_accepts_raw_string_and_object_fields() {
        assert_eq!(
            patch_source_from_args(&json!("*** Begin Patch\n*** End Patch\n")),
            Some("*** Begin Patch\n*** End Patch\n")
        );
        assert_eq!(patch_source_from_args(&json!({"input": "x"})), Some("x"));
        assert_eq!(patch_source_from_args(&json!({"patch": "y"})), Some("y"));
    }

    #[test]
    fn patch_source_prefers_patch_shaped_field_when_both_present() {
        // When both `input` and `patch` are present, prefer the one whose
        // content actually looks like a VTE patch. This prevents a non-patch
        // `input` (raw file contents) from masking a valid `patch` field.
        let raw_source = "pub fn foo() { println!(\"hi\"); }\n";
        let vte_patch = "*** Begin Patch\n*** Update File: f.rs\n@@\n-old\n+new\n*** End Patch";

        // `input` = raw source, `patch` = real patch → prefer `patch`.
        let args = json!({ "input": raw_source, "patch": vte_patch });
        assert_eq!(patch_source_from_args(&args), Some(vte_patch));

        // `input` = real patch, `patch` = raw source → prefer `input`.
        let args = json!({ "input": vte_patch, "patch": raw_source });
        assert_eq!(patch_source_from_args(&args), Some(vte_patch));

        // Neither is patch-shaped → fall back to `input`-first (historical).
        let args = json!({ "input": "aaa", "patch": "bbb" });
        assert_eq!(patch_source_from_args(&args), Some("aaa"));
    }

    #[test]
    fn decode_apply_patch_input_supports_base64_payloads() {
        let payload = json!({
            "patch": "base64:KioqIEJlZ2luIFBhdGNoCioqKiBFbmQgUGF0Y2gK"
        });

        let decoded = decode_apply_patch_input(&payload)
            .expect("payload should decode")
            .expect("payload should be present");

        assert_eq!(decoded.text, "*** Begin Patch\n*** End Patch\n");
        assert_eq!(decoded.source_bytes, 47);
        assert!(decoded.was_base64);
    }

    #[test]
    fn mutation_paths_cover_all_public_patch_operations_and_alias_shapes() {
        use base64::Engine;
        use base64::engine::general_purpose::STANDARD as BASE64;

        let patch = "*** Begin Patch\n*** Add File: src/add.rs\n+new\n*** Delete File: src/delete.rs\n*** Update File: src/old.rs\n*** Move to: src/new.rs\n@@\n-old\n+new\n*** End Patch\n";
        let expected = vec![
            PathBuf::from("src/add.rs"),
            PathBuf::from("src/delete.rs"),
            PathBuf::from("src/new.rs"),
            PathBuf::from("src/old.rs"),
        ];

        assert_eq!(mutation_target_paths("apply_patch", &json!(patch)), expected);
        assert_eq!(mutation_target_paths("apply_patch", &json!({"input": patch})), expected);
        assert_eq!(
            mutation_target_paths("apply_patch", &json!({"patch": format!("base64:{}", BASE64.encode(patch))}),),
            expected
        );

        let duplicate_patch = super::Patch::parse(
            "*** Begin Patch\n*** Update File: src/same.rs\n*** Move to: src/same.rs\n@@\n-old\n+new\n*** End Patch\n",
        )
        .expect("duplicate-path patch should parse");
        assert_eq!(patch_mutation_target_paths(&duplicate_patch), vec![PathBuf::from("src/same.rs")]);
    }

    #[test]
    fn mutation_paths_include_move_and_copy_destinations() {
        assert_eq!(
            mutation_target_paths("move_file", &json!({"path": "src/old.rs", "destination": "src/new.rs"}),),
            vec![PathBuf::from("src/old.rs"), PathBuf::from("src/new.rs")]
        );
        assert_eq!(
            mutation_target_paths(
                "copy_file",
                &json!({
                    "file_path": "src/original.rs",
                    "destination_path": "src/copy.rs"
                }),
            ),
            vec![PathBuf::from("src/original.rs"), PathBuf::from("src/copy.rs")]
        );
    }

    #[test]
    fn decode_apply_patch_input_rejects_invalid_base64() {
        let error =
            decode_apply_patch_input(&json!({"input": "base64:not-valid"})).expect_err("invalid base64 should fail");

        assert!(error.to_string().contains("Failed to decode base64 patch"));
    }

    #[test]
    fn decode_apply_patch_input_caps_decoded_size() {
        use base64::Engine;
        // Build a 1.5 MiB decoded payload via base64. The default cap is 1 MiB so the
        // decode must fail with the post-decode size error rather than producing the
        // oversized text.
        let large = "A".repeat(1_500_000);
        let encoded = base64::engine::general_purpose::STANDARD.encode(large.as_bytes());
        let payload = json!({ "input": format!("base64:{encoded}") });

        let error = decode_apply_patch_input(&payload).expect_err("oversized decoded payload should be rejected");
        let message = error.to_string();
        assert!(
            message.contains("apply_patch payload too large after decoding"),
            "unexpected error message: {message}"
        );
        assert!(message.contains("base64=true"));
    }

    #[test]
    fn decode_apply_patch_input_caps_raw_payload_size() {
        // Even non-base64 inputs must respect the cap. Build a 1.5 MiB raw string
        // and confirm it is rejected.
        let large = "B".repeat(1_500_000);
        let payload = json!({ "input": large });

        let error = decode_apply_patch_input(&payload).expect_err("oversized raw payload should be rejected");
        let message = error.to_string();
        assert!(
            message.contains("apply_patch payload too large after decoding"),
            "unexpected error message: {message}"
        );
        assert!(message.contains("base64=false"));
    }

    #[test]
    fn semantic_anchor_guidance_is_appended_once() {
        let base = "Patch in VT Code format.";
        let with_guidance = with_semantic_anchor_guidance(base);
        assert!(with_guidance.contains(SEMANTIC_ANCHOR_GUIDANCE));
        assert_eq!(with_semantic_anchor_guidance(&with_guidance), with_guidance, "guidance should not be duplicated");
    }

    #[test]
    fn parameter_schema_keeps_alias_and_guidance_consistent() {
        let schema = parameter_schema("Patch in VT Code format");

        // Both `input` and `patch` are alias fields for the same payload, so
        // both must carry the format description AND the semantic-anchor
        // guidance. This prevents the model from placing a unified diff in
        // `patch` (see checkpoint turn_615).
        assert_eq!(
            schema["properties"]["patch"]["description"],
            with_semantic_anchor_guidance(APPLY_PATCH_ALIAS_DESCRIPTION)
        );
        let patch_description = schema["properties"]["patch"]["description"]
            .as_str()
            .expect("patch description");
        assert!(patch_description.contains("*** Begin Patch"), "patch description must name the envelope format");
        assert!(patch_description.contains("unified diff"), "patch description must warn against unified diff");
        assert!(patch_description.contains(SEMANTIC_ANCHOR_GUIDANCE));

        let input_description = schema["properties"]["input"]["description"]
            .as_str()
            .expect("input description");
        assert!(input_description.contains(SEMANTIC_ANCHOR_GUIDANCE));
    }
}