//! Snapshot test pinning the `Vec<Chunk>` JSON for a
//! representative Rust code `CanonicalDocument`.
//!
//! This is an integration test. `kebab-parse-code` is intentionally NOT
//! a dev-dep (design §6.3 / §8 boundary: AST extraction is parser-side).
//! The `CanonicalDocument` is built inline from hand-crafted `Block::Code`
//! units, which is the same pattern used in `code_rust_ast_v1.rs`'s
//! internal `code_doc` test helper.
//!
//! Set `UPDATE_SNAPSHOTS=1` to re-bake the baseline.

use std::path::PathBuf;

use kebab_chunk::CodeRustAstV1Chunker;
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 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("crates/kebab-chunk/src/code_rust_ast_v1.rs".into());
    let aid = AssetId("b".repeat(64));
    // Pin parser_version so doc_id / block_ids are reproducible.
    let pv = ParserVersion("code-rust-v1".into());
    let doc_id = id_for_doc(&wp, &aid, &pv);

    // Build a >200-line function body to force split_oversize.
    let big_body: String = {
        let header = "pub fn big_fn(input: &[u8]) -> Vec<u8> {\n";
        let body: String = (0..210u32)
            .map(|i| format!("    let v{i} = input.get({i} as usize).copied().unwrap_or(0);\n"))
            .collect();
        let footer = "    vec![0u8]\n}";
        format!("{header}{body}{footer}")
    };
    let big_line_count = big_body.lines().count() as u32;
    let big_line_end = 48 + big_line_count - 1;

    // Representative units:
    //  0. top-level use+const block  (lines 1–5,   ≤200)
    //  1. free fn `parse`            (lines 7–12,  ≤200)
    //  2. struct `Foo`               (lines 14–20, ≤200)
    //  3. trait `Frobable`           (lines 22–30, ≤200)
    //  4. impl Foo::double           (lines 32–38, ≤200)
    //  5. impl Foo::triple           (lines 40–46, ≤200)
    //  6. big_fn (>200 lines)        to force split_oversize
    let raw_units: Vec<(&str, u32, u32, String)> = vec![
        (
            "use+const",
            1,
            5,
            "use std::collections::HashMap;\nuse std::fmt;\n\nconst MAX: usize = 1024;\nconst MIN: usize = 0;".to_string(),
        ),
        (
            "parse",
            7,
            12,
            "pub fn parse(input: &str) -> Option<u32> {\n    input\n        .trim()\n        .parse()\n        .ok()\n}".to_string(),
        ),
        (
            "Foo",
            14,
            20,
            "pub struct Foo {\n    pub name: String,\n    pub value: u32,\n    pub tags: Vec<String>,\n    pub meta: Option<String>,\n    pub count: usize,\n}".to_string(),
        ),
        (
            "Frobable",
            22,
            30,
            "pub trait Frobable {\n    fn frob(&self) -> String;\n    fn frob_twice(&self) -> String {\n        let a = self.frob();\n        let b = self.frob();\n        format!(\"{a}{b}\")\n    }\n    fn name(&self) -> &str;\n}".to_string(),
        ),
        (
            "Foo::double",
            32,
            38,
            "impl Foo {\n    pub fn double(&self) -> u32 {\n        self.value\n            .checked_mul(2)\n            .unwrap_or(u32::MAX)\n    }\n}".to_string(),
        ),
        (
            "Foo::triple",
            40,
            46,
            "impl Foo {\n    pub fn triple(&self) -> u32 {\n        self.value\n            .checked_mul(3)\n            .unwrap_or(u32::MAX)\n    }\n}".to_string(),
        ),
        ("big_fn", 48, big_line_end, big_body),
    ];

    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("rust".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("rust".into()),
                code: code.clone(),
            })
        })
        .collect();

    CanonicalDocument {
        doc_id,
        source_asset_id: aid,
        workspace_path: wp,
        title: "code_rust_ast_v1.rs".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("rust".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-rust-ast-v1".into()),
    }
}

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

    let chunks = CodeRustAstV1Chunker.chunk(&doc, &policy).expect("chunk");
    let actual = serde_json::to_value(&chunks).unwrap();

    let dir = fixtures_dir();
    let baseline_path = dir.join("code-sample.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-rust-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_rust_ast_chunks_are_deterministic() {
    let policy = fixed_policy();
    let baseline: Vec<String> = CodeRustAstV1Chunker
        .chunk(&fixed_doc(), &policy)
        .unwrap()
        .into_iter()
        .map(|c| c.chunk_id.0)
        .collect();
    for _ in 0..5 {
        let again: Vec<String> = CodeRustAstV1Chunker
            .chunk(&fixed_doc(), &policy)
            .unwrap()
            .into_iter()
            .map(|c| c.chunk_id.0)
            .collect();
        assert_eq!(again, baseline);
    }
}