//! Snapshot test pinning the `Vec<Chunk>` JSON for a
//! representative C++ code `CanonicalDocument`.
//!
//! Two complementary tests:
//! 1. `code_cpp_ast_chunks_snapshot` — hand-built `fixed_doc()` validates the
//!    chunker's 1:1 mapping (design §6.3 / §8 boundary: no parse-code dep needed).
//! 2. `code_cpp_ast_extractor_snapshot` — invokes `CppAstExtractor` against the
//!    real `tests/fixtures/sample.cpp` fixture, validating the extractor → chunker
//!    end-to-end pipeline. `kebab-parse-code` is a dev-dep (same pattern as
//!    `kebab-parse-md` in Markdown snapshot tests).
//!
//! Set `UPDATE_SNAPSHOTS=1` to re-bake the baseline.

use std::path::PathBuf;

use kebab_chunk::CodeCppAstV1Chunker;
use kebab_core::{
    AssetId, Block, CanonicalDocument, ChunkPolicy, Chunker, ChunkerVersion, CodeBlock, CommonBlock,
    Lang, Metadata, ParserVersion, Provenance, SourceSpan, SourceType, TrustLevel, WorkspacePath,
    id_for_block, id_for_doc,
};
use kebab_parse_code::CppAstExtractor;
use serde_json::Value;
use time::OffsetDateTime;

fn fixtures_dir() -> PathBuf {
    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
        .join("tests")
        .join("fixtures")
}

fn fixed_doc() -> CanonicalDocument {
    let wp = WorkspacePath("projects/record.cpp".into());
    let aid = AssetId("c".repeat(64));
    // Pin parser_version so doc_id / block_ids are reproducible.
    let pv = ParserVersion("code-cpp-v1".into());
    let doc_id = id_for_doc(&wp, &aid, &pv);

    // Representative units (C++ specific):
    //  0. includes + namespace opening  (lines 1–4,   ≤200)
    //  1. class definition              (lines 6–20,  ≤200)
    //  2. template function             (lines 22–25, ≤200)
    //  3. namespace closing + free fn   (lines 27–29, ≤200)
    //  4. main fn                       (lines 31–34, ≤200)
    let raw_units: Vec<(&str, u32, u32, String)> = vec![
        (
            "<top-level>",
            1,
            4,
            "#include <string>\n#include <vector>\n\nnamespace kebab {".to_string(),
        ),
        (
            "kebab::chunk::MdHeadingV1Chunker",
            6,
            20,
            "class MdHeadingV1Chunker {\npublic:\n    MdHeadingV1Chunker() = default;\n    ~MdHeadingV1Chunker() = default;\n\n    std::string chunk_doc(const std::string& doc) {\n        return doc;\n    }\n\n    int operator()(int x) const {\n        return x * 2;\n    }\n\nprivate:\n    int counter_ = 0;\n};".to_string(),
        ),
        (
            "kebab::identity",
            22,
            25,
            "template <typename T>\nT identity(T value) {\n    return value;\n}".to_string(),
        ),
        (
            "kebab::global_helper",
            27,
            29,
            "void global_helper() {\n    // free function in kebab namespace\n}".to_string(),
        ),
        (
            "main",
            31,
            34,
            "int main() {\n    kebab::chunk::MdHeadingV1Chunker c;\n    return 0;\n}".to_string(),
        ),
    ];

    let blocks: Vec<Block> = raw_units
        .iter()
        .enumerate()
        .map(|(i, (sym, ls, le, code))| {
            let span = SourceSpan::Code {
                line_start: *ls,
                line_end: *le,
                symbol: Some((*sym).to_string()),
                lang: Some("cpp".into()),
            };
            let bid = id_for_block(&doc_id, "code", &[], i as u32, &span);
            Block::Code(CodeBlock {
                common: CommonBlock {
                    block_id: bid,
                    heading_path: vec![],
                    source_span: span,
                },
                lang: Some("cpp".into()),
                code: code.clone(),
            })
        })
        .collect();

    CanonicalDocument {
        doc_id,
        source_asset_id: aid,
        workspace_path: wp,
        title: "record.cpp".into(),
        lang: Lang("und".into()),
        blocks,
        metadata: Metadata {
            aliases: vec![],
            tags: vec![],
            created_at: OffsetDateTime::from_unix_timestamp(1_700_000_000).unwrap(),
            updated_at: OffsetDateTime::from_unix_timestamp(1_700_000_000).unwrap(),
            source_type: SourceType::Note,
            trust_level: TrustLevel::Primary,
            user_id_alias: None,
            user: Default::default(),
            repo: Some("kebab".into()),
            git_branch: Some("main".into()),
            git_commit: Some("0".repeat(40)),
            code_lang: Some("cpp".into()),
        },
        provenance: Provenance { events: vec![] },
        parser_version: pv,
        schema_version: 1,
        doc_version: 1,
        last_chunker_version: None,
        last_embedding_version: None,
    }
}

fn fixed_policy() -> ChunkPolicy {
    ChunkPolicy {
        target_tokens: 500,
        overlap_tokens: 80,
        respect_markdown_headings: false,
        chunker_version: ChunkerVersion("code-cpp-ast-v1".into()),
    }
}

// ---------------------------------------------------------------------------
// Helper: run the real CppAstExtractor against tests/fixtures/sample.cpp
// ---------------------------------------------------------------------------

fn extract_cpp_fixture() -> CanonicalDocument {
    use kebab_core::{
        AssetId, AssetStorage, Checksum, ExtractConfig, ExtractContext, Extractor, RawAsset,
        SourceUri, WorkspacePath,
    };
    use std::path::PathBuf;

    let bytes = std::fs::read(fixtures_dir().join("sample.cpp")).expect("read sample.cpp fixture");
    let src = String::from_utf8(bytes).expect("fixture is valid UTF-8");
    let wp = WorkspacePath("tests/fixtures/sample.cpp".to_string());
    let asset = RawAsset {
        asset_id: AssetId("e".repeat(64)),
        source_uri: SourceUri::File(PathBuf::from("tests/fixtures/sample.cpp")),
        workspace_path: wp,
        media_type: kebab_core::MediaType::Code("cpp".to_string()),
        byte_len: src.len() as u64,
        checksum: Checksum("f".repeat(64)),
        discovered_at: time::OffsetDateTime::from_unix_timestamp(1_700_000_000).unwrap(),
        stored: AssetStorage::Reference {
            path: PathBuf::from("tests/fixtures/sample.cpp"),
            sha: Checksum("f".repeat(64)),
        },
    };
    let cfg = ExtractConfig::default();
    let root = PathBuf::from("/tmp");
    let ctx = ExtractContext {
        asset: &asset,
        workspace_root: &root,
        config: &cfg,
    };
    CppAstExtractor::new().extract(&ctx, src.as_bytes()).unwrap()
}

// ---------------------------------------------------------------------------
// Test 1 (hand-built): chunker-only 1:1 mapping validation
// ---------------------------------------------------------------------------

#[test]
fn code_cpp_ast_chunks_snapshot() {
    let doc = fixed_doc();
    let policy = fixed_policy();

    let chunks = CodeCppAstV1Chunker.chunk(&doc, &policy).expect("chunk");
    let actual = serde_json::to_value(&chunks).unwrap();

    let dir = fixtures_dir();
    let baseline_path = dir.join("code-sample.cpp.chunks.snapshot.json");
    let baseline_text = match std::fs::read_to_string(&baseline_path) {
        Ok(s) => s,
        Err(_) if std::env::var("UPDATE_SNAPSHOTS").is_ok() => {
            std::fs::create_dir_all(&dir).unwrap();
            let pretty = serde_json::to_string_pretty(&actual).unwrap();
            std::fs::write(&baseline_path, format!("{pretty}\n")).unwrap();
            return;
        }
        Err(e) => panic!(
            "missing baseline {}; run with UPDATE_SNAPSHOTS=1 to create: {e}",
            baseline_path.display()
        ),
    };
    let expected: Value = serde_json::from_str(&baseline_text).expect("baseline parses as json");

    if actual != expected {
        if std::env::var("UPDATE_SNAPSHOTS").is_ok() {
            let pretty = serde_json::to_string_pretty(&actual).unwrap();
            std::fs::write(&baseline_path, format!("{pretty}\n")).unwrap();
            eprintln!("updated baseline {}", baseline_path.display());
            return;
        }
        let pretty = serde_json::to_string_pretty(&actual).unwrap();
        panic!(
            "code-cpp-ast-v1 chunks snapshot drift\n\
             --- expected ({}) ---\n{baseline_text}\n\
             --- actual ---\n{pretty}\n\
             If intentional, re-run with UPDATE_SNAPSHOTS=1.",
            baseline_path.display()
        );
    }
}

/// Determinism cross-check: re-running the same pipeline yields the same
/// chunk_ids byte-for-byte.
#[test]
fn code_cpp_ast_chunks_are_deterministic() {
    let policy = fixed_policy();
    let baseline: Vec<String> = CodeCppAstV1Chunker
        .chunk(&fixed_doc(), &policy)
        .unwrap()
        .into_iter()
        .map(|c| c.chunk_id.0)
        .collect();
    for _ in 0..5 {
        let again: Vec<String> = CodeCppAstV1Chunker
            .chunk(&fixed_doc(), &policy)
            .unwrap()
            .into_iter()
            .map(|c| c.chunk_id.0)
            .collect();
        assert_eq!(again, baseline);
    }
}

// ---------------------------------------------------------------------------
// Test 2 (real extractor): end-to-end extractor → chunker pipeline
// ---------------------------------------------------------------------------

/// Validates that the real `CppAstExtractor` processes `sample.cpp` and
/// emits the expected set of symbols through the full chunker pipeline.
///
/// `sample.cpp` contains:
/// - `#include` directives + nested namespace `kebab::chunk` → glue + struct unit
/// - `class MdHeadingV1Chunker` with methods (ctor, dtor, chunk_doc, operator())
/// - `template <typename T> T identity(T value)` (template fn)
/// - `void kebab::global_helper()` (free fn in namespace)
/// - `int main()` (global free fn)
#[test]
fn code_cpp_ast_extractor_snapshot() {
    let doc = extract_cpp_fixture();

    // Verify the extractor emits all expected named units.
    let block_syms: Vec<Option<String>> = doc.blocks.iter().filter_map(|b| match b {
        Block::Code(c) => match &c.common.source_span {
            SourceSpan::Code { symbol, .. } => Some(symbol.clone()),
            _ => None,
        },
        _ => None,
    }).collect();

    // Must include namespace-qualified class and its methods
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("kebab::chunk::MdHeadingV1Chunker")),
        "class unit missing: {block_syms:?}"
    );
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("kebab::chunk::MdHeadingV1Chunker::MdHeadingV1Chunker")),
        "ctor unit missing: {block_syms:?}"
    );
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("kebab::chunk::MdHeadingV1Chunker::~MdHeadingV1Chunker")),
        "dtor unit missing: {block_syms:?}"
    );
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("kebab::chunk::MdHeadingV1Chunker::chunk_doc")),
        "chunk_doc unit missing: {block_syms:?}"
    );
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("kebab::chunk::MdHeadingV1Chunker::operator()")),
        "operator() unit missing: {block_syms:?}"
    );
    // Template function (inside kebab::chunk namespace in the fixture)
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("kebab::chunk::identity")),
        "identity template fn unit missing: {block_syms:?}"
    );
    // Free function in outer namespace
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("kebab::global_helper")),
        "global_helper unit missing: {block_syms:?}"
    );
    // Global main
    assert!(
        block_syms.iter().any(|s| s.as_deref() == Some("main")),
        "main unit missing: {block_syms:?}"
    );
}

/// End-to-end chunker output from real extractor is deterministic.
#[test]
fn code_cpp_ast_extractor_chunks_deterministic() {
    let doc1 = extract_cpp_fixture();
    let doc2 = extract_cpp_fixture();
    assert_eq!(doc1.blocks, doc2.blocks, "extractor output non-deterministic");

    let policy = fixed_policy();
    let chunks1 = CodeCppAstV1Chunker.chunk(&doc1, &policy).unwrap();
    let chunks2 = CodeCppAstV1Chunker.chunk(&doc2, &policy).unwrap();
    assert_eq!(
        chunks1.iter().map(|c| c.chunk_id.0.clone()).collect::<Vec<_>>(),
        chunks2.iter().map(|c| c.chunk_id.0.clone()).collect::<Vec<_>>(),
        "chunker output non-deterministic"
    );
}