pushkin-core 0.2.0

//! The deterministic per-write validation pipeline (spec §8.2, Phase 1
//! subset: contract conformance heuristic, suppression detection, protected
//! paths), driven by the manifest instead of Phase 0's hardcoded settings.
//! Rule IDs and decisions are conformance-locked to the Phase 0 Bun spike.

use crate::envelope::{CheckResult, Decision, Severity, Violation};
use crate::manifest::Manifest;

pub const RULE_UNVALIDATED_INPUT: &str = "contract.boundary.unvalidated_input";
pub const RULE_NEW_SUPPRESSION: &str = "pushkin.suppression.new";
pub const RULE_PROTECTED_PATH: &str = "pushkin.protected_path";
pub const RULE_READ_ONLY_PATH: &str = "pushkin.read_only_path";
pub const RULE_RAW_READ: &str = "pushkin.retrieval.raw_read";
/// F48 Phase A — a content-requiring rule could not be evaluated because the
/// mutation carried no content. DISTINCT from `RULE_UNVALIDATED_INPUT` on
/// purpose: an event log must be able to separate "we could not look" from
/// "we looked and it was wrong", and Phase B's exit evidence depends on that
/// separation. Waivable, like its contract-rule sibling — the posture forbids
/// a SILENT allow, not a loud recorded exception.
pub const RULE_CONTENT_UNAVAILABLE: &str = "pushkin.content_unavailable";

const SUPPRESSION_MARKERS: &[&str] = &[
    "@ts-ignore",
    "@ts-expect-error",
    "@ts-nocheck",
    "eslint-disable",
    "noqa",
    "type: ignore",
];

const HANDLER_METHODS: &[&str] = &["GET", "POST", "PUT", "PATCH", "DELETE"];

pub struct WriteRequest {
    pub file_path: String,
    pub content: String,
}

#[must_use]
pub fn check_write(manifest: &Manifest, request: &WriteRequest) -> CheckResult {
    let started = std::time::Instant::now();
    let mut violations = Vec::new();

    violations.extend(check_protected_path(manifest, request));
    violations.extend(check_suppressions(manifest, request));
    violations.extend(check_boundary_validation(manifest, request));

    CheckResult {
        decision: if violations.is_empty() {
            Decision::Allow
        } else {
            Decision::Block
        },
        violations,
        duration_ms: started.elapsed().as_secs_f64() * 1000.0,
    }
}

/// F48 Phase A — the pipeline for a MUTATION that carries no content
/// (`Edit`'s `old_string`/`new_string`, `MultiEdit`'s `edits[]`). Sibling of
/// `check_write`, and deliberately not a special case inside it: the two take
/// different inputs and answer different questions.
///
/// Path-decidable rules run exactly as they do for a write, because they never
/// needed content — a glob is a glob. Content-requiring rules cannot run at
/// all, so they deny under `RULE_CONTENT_UNAVAILABLE` rather than being
/// skipped. **Skipping was the defect** (F48): `check_write` with an empty
/// content string silently passes `check_suppressions` and
/// `check_boundary_validation`, because neither finds anything to object to in
/// zero bytes, so a content-absent mutation used to look clean.
///
/// The `read_only_paths` half is the CLI's, as always — core stays free of git.
#[must_use]
pub fn check_mutation_without_content(
    manifest: &Manifest,
    file_path: &str,
    tool: &str,
) -> CheckResult {
    let started = std::time::Instant::now();
    let mut violations = check_mutation_path_rules(manifest, file_path);

    // A mapping declaring a content requirement is the trigger: the rule
    // exists for this path, and this payload cannot satisfy it either way.
    if let Some(mapping) = manifest.mapping_for(file_path) {
        if let Some(requirement) = mapping.require.as_deref() {
            violations.push(content_unavailable_violation(file_path, tool, requirement));
        }
    }

    CheckResult {
        decision: if violations.is_empty() {
            Decision::Allow
        } else {
            Decision::Block
        },
        violations,
        duration_ms: started.elapsed().as_secs_f64() * 1000.0,
    }
}

/// The path-decidable half of a mutation's verdict — the rules that never
/// needed content. Split out so F48 Phase B can run them BEFORE attempting a
/// reconstruction: a path rule must fire whatever the edits would have
/// produced, and must never be masked by a reconstruction failure.
#[must_use]
pub fn check_mutation_path_rules(manifest: &Manifest, file_path: &str) -> Vec<Violation> {
    check_protected_path(
        manifest,
        &WriteRequest {
            file_path: file_path.to_owned(),
            content: String::new(),
        },
    )
}

/// F48 Phase B — the outcome of trying to reconstruct a post-edit file.
pub enum Synthesis {
    /// The file was read and the edits applied; judge this content.
    Content(String),
    /// No faithful reconstruction was possible. The string explains why, and
    /// the caller must fall back to the interim refusal — never to an allow.
    Refused(String),
}

/// F48 Phase B — reconstruct the file `edits` would produce from `on_disk`.
///
/// Pure with respect to the filesystem: the caller reads the file (core stays
/// free of I/O) and passes what it found, or `None` when it could not be read.
/// A create-shaped edit against a file that does not exist is `Refused`, not an
/// empty-content write — the replacement text is not the file.
///
/// **Every failure is `Refused`.** That is the whole safety property: Phase A
/// refused when there was no content, and Phase B refuses when there is no
/// FAITHFUL content. Returning a best-effort string here is precisely how
/// fail-closed becomes false-allow.
#[must_use]
pub fn synthesize(on_disk: Option<&str>, edits: &[crate::edits::Replacement]) -> Synthesis {
    if edits.is_empty() {
        return Synthesis::Refused(
            "the mutation carries no reconstructable edit operations".to_owned(),
        );
    }
    let Some(content) = on_disk else {
        return Synthesis::Refused(
            "the target file could not be read, so there is nothing to apply the edits to"
                .to_owned(),
        );
    };
    match crate::edits::apply_edits(content, edits) {
        Ok(result) => Synthesis::Content(result),
        Err(error) => Synthesis::Refused(error.to_string()),
    }
}

/// The interim-conservative refusal. Names the tool, the rule that could not
/// be evaluated, and the remediation — a deny an agent cannot act on is just
/// an obstacle.
#[must_use]
pub fn content_unavailable_violation(path: &str, tool: &str, requirement: &str) -> Violation {
    let blocked = if requirement == "boundary-validation" {
        RULE_UNVALIDATED_INPUT
    } else {
        requirement
    };
    Violation {
        file: path.to_owned(),
        line: 1,
        rule: RULE_CONTENT_UNAVAILABLE.to_owned(),
        contract: None,
        fix_hint: format!(
            "`{tool}` carries no file content, so `{blocked}` could not be evaluated for \
             this path. This is an INTERIM-CONSERVATIVE refusal (F48 Phase A): the gate \
             refuses rather than allowing a content rule it could not check. Re-issue the \
             change as a Write carrying the full file content, and the rule will be \
             evaluated normally."
        ),
        suggestions: vec![
            "Re-issue as Write with the complete file content.".to_owned(),
            "Content synthesis (F48 Phase B) is live for EVERY edit tool: Claude's \
             Edit/MultiEdit, auggie's str-replace-editor, opencode's edit, hermes' \
             patch and codex's apply_patch hunks. A refusal here therefore means the \
             RECONSTRUCTION failed — see the reason above — not that synthesis is \
             unavailable. Two families reconstruct on narrower terms: hermes needs an \
             EXACT unique match because its own matcher is fuzzy, and a codex hunk \
             needs a unique context because its `@@` scope header is a locator this \
             gate does not resolve."
                .to_owned(),
        ],
        severity: Severity::Error,
    }
}

/// `pushkin/` (waivers, adapter configs, bindings) is gate surface by
/// construction (integration doc §7: "agents cannot waive"), independent of
/// what the manifest lists.
const BUILTIN_PROTECTED_PREFIX: &str = "pushkin/";

fn check_protected_path(manifest: &Manifest, request: &WriteRequest) -> Vec<Violation> {
    let builtin = request.file_path.starts_with(BUILTIN_PROTECTED_PREFIX);
    if !builtin && !manifest.is_protected(&request.file_path) {
        return Vec::new();
    }
    vec![Violation {
        file: request.file_path.clone(),
        line: 1,
        rule: RULE_PROTECTED_PATH.to_owned(),
        contract: None,
        fix_hint: "This path is part of Pushkin's own gate surface and may not be edited \
                   by agents. If the change is genuinely required, a human must make it."
            .to_owned(),
        suggestions: vec!["Ask the human operator to apply this change manually.".to_owned()],
        severity: Severity::Error,
    }]
}

/// The protected-path violation, raised by the pre-commit floor when the
/// event log shows an agent was denied this exact path and it is staged
/// anyway. Built here so the rule id and wording stay beside their
/// siblings; the CLI owns the evidence predicate, since core stays free of
/// git and the filesystem.
///
/// The prose differs from the write-time deny on purpose: by the time the
/// floor sees it the edit already exists in the tree, so the instruction is
/// to unstage rather than to not write.
#[must_use]
pub fn protected_path_bypass_violation(path: &str) -> Violation {
    Violation {
        file: path.to_owned(),
        line: 1,
        rule: RULE_PROTECTED_PATH.to_owned(),
        contract: None,
        fix_hint: "An agent was denied a write to this protected path, and it is staged \
                   anyway — the edit reached the tree through a surface the write gate \
                   never saw. A human must own this change."
            .to_owned(),
        suggestions: vec![
            format!("git restore --staged --worktree {path}"),
            "Or, if the change is genuinely required, apply it yourself and commit with \
             --no-verify."
                .to_owned(),
        ],
        severity: Severity::Error,
    }
}

/// The violation for an agent write to a COMMITTED file under a
/// `read_only_paths` glob. Built here so the rule id and wording live
/// beside their siblings, but raised by the CLI layer, which owns the
/// committed-in-HEAD predicate — core stays free of git and the
/// filesystem.
#[must_use]
pub fn read_only_violation(path: &str) -> Violation {
    Violation {
        file: path.to_owned(),
        line: 1,
        rule: RULE_READ_ONLY_PATH.to_owned(),
        contract: None,
        fix_hint: "This file is committed under a read-only path (N10: committed suites \
                   are read-only). Agents may add NEW files here; a committed file only \
                   a human may change."
            .to_owned(),
        suggestions: vec![
            "Author a new file for new coverage, or ask the human operator to apply \
             this edit manually."
                .to_owned(),
        ],
        severity: Severity::Error,
    }
}

/// SPIKE — the violation for an UNBOUNDED agent read of a file under a
/// `retrieval_paths` glob. Sibling of `read_only_violation`: built here so
/// the rule id and wording sit beside the others, raised by the CLI layer,
/// which owns the read-shape predicate.
///
/// `tool` is whatever the manifest declares, so the prose redirects to the
/// repo's chosen index rather than a vendor baked into this crate.
#[must_use]
pub fn raw_read_violation(path: &str, tool: Option<&str>) -> Violation {
    let destination = tool.unwrap_or("the repository's retrieval tool");
    Violation {
        file: path.to_owned(),
        line: 1,
        rule: RULE_RAW_READ.to_owned(),
        contract: None,
        fix_hint: format!(
            "Whole-file reads of this path are gated. Ask {destination} for the \
             code you need, or re-issue this read with an explicit offset and \
             limit naming the range you are about to work on."
        ),
        suggestions: vec![
            format!("Retrieve it: {destination}"),
            "Or read a range: Read(file_path, offset, limit).".to_owned(),
        ],
        severity: Severity::Error,
    }
}

fn check_suppressions(manifest: &Manifest, request: &WriteRequest) -> Vec<Violation> {
    if manifest.mapping_for(&request.file_path).is_none() {
        return Vec::new();
    }
    let mut violations = Vec::new();
    for (index, line_text) in request.content.lines().enumerate() {
        let Some(marker) = SUPPRESSION_MARKERS.iter().find(|m| line_text.contains(**m)) else {
            continue;
        };
        violations.push(Violation {
            file: request.file_path.clone(),
            line: to_line_number(index),
            rule: RULE_NEW_SUPPRESSION.to_owned(),
            contract: None,
            fix_hint: format!(
                "Remove the suppression comment ('{marker}') and fix the underlying issue instead."
            ),
            suggestions: vec![
                "Fix the reported type/lint error rather than silencing it.".to_owned()
            ],
            severity: Severity::Error,
        });
    }
    violations
}

fn check_boundary_validation(manifest: &Manifest, request: &WriteRequest) -> Vec<Violation> {
    let Some(mapping) = manifest.mapping_for(&request.file_path) else {
        return Vec::new();
    };
    if mapping.require.as_deref() != Some("boundary-validation") {
        return Vec::new();
    }
    let Some(handler_line) = find_handler_line(&request.content) else {
        return Vec::new();
    };
    if parses_with_contract(&request.content) {
        return Vec::new();
    }
    let contract = mapping.contracts.first().map(|c| c.as_str().to_owned());
    let schema_name = schema_symbol(contract.as_deref());
    vec![Violation {
        file: request.file_path.clone(),
        line: handler_line,
        rule: RULE_UNVALIDATED_INPUT.to_owned(),
        contract: contract.clone(),
        fix_hint: format!(
            "Parse the request body with {schema_name} (contract '{}') before use — e.g. \
             const body = {schema_name}.parse(await req.json()); — fix and retry the write.",
            contract.as_deref().unwrap_or("unknown")
        ),
        suggestions: vec![
            format!("import {{ {schema_name} }} from \"contracts/user.zod\""),
            format!("contract_show {}", contract.as_deref().unwrap_or("unknown")),
        ],
        severity: Severity::Error,
    }]
}

/// Phase 0 parity: `UserCreateSchema` for contract `user`. Phase 3's
/// symbol-level mapper generalizes this; until then the convention is
/// `<PascalCase contract>CreateSchema`.
fn schema_symbol(contract: Option<&str>) -> String {
    let name = contract.unwrap_or("unknown");
    let mut pascal = String::new();
    for part in name.split(['-', '_']) {
        let mut chars = part.chars();
        if let Some(first) = chars.next() {
            pascal.extend(first.to_uppercase());
            pascal.push_str(chars.as_str());
        }
    }
    format!("{pascal}CreateSchema")
}

fn find_handler_line(content: &str) -> Option<u32> {
    for (index, line_text) in content.lines().enumerate() {
        let is_export = line_text.contains("export");
        let is_function = line_text.contains("function") || line_text.contains("async function");
        if is_export
            && is_function
            && HANDLER_METHODS
                .iter()
                .any(|method| line_text.contains(method))
        {
            return Some(to_line_number(index));
        }
    }
    None
}

fn parses_with_contract(content: &str) -> bool {
    content.lines().any(|line_text| {
        let Some(schema_pos) = line_text.find("Schema") else {
            return false;
        };
        let rest = &line_text[schema_pos..];
        rest.contains(".parse") || rest.contains(".safeParse")
    })
}

fn to_line_number(index: usize) -> u32 {
    u32::try_from(index)
        .unwrap_or(u32::MAX - 1)
        .saturating_add(1)
}