use serde_json::{json, Value};
use std::path::{Path, PathBuf};

pub fn default_tdd_schema_path() -> PathBuf {
    let rust_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
    let repo_root = rust_dir.parent().unwrap_or(&rust_dir);
    repo_root.join("website/generated/tdd-schema.json")
}

pub fn tdd_schema_value() -> Value {
    json!({
        "schema_version": 1,
        "format": "nebu-ctx-tdd",
        "crp": {
            "modes": [
                {
                    "name": "off",
                    "description": "No CRP transformation."
                },
                {
                    "name": "compact",
                    "description": "Compact prose; prefer bullet points and short lines."
                },
                {
                    "name": "tdd",
                    "description": "Token Dense Dialect: max information density, minimal narration."
                }
            ],
            "output_rules": [
                "Prefer structured bullets over paragraphs.",
                "Avoid repeating previously shown context.",
                "Show diffs instead of full files when possible.",
                "For code reads, prefer map/signatures/task over full."
            ]
        },
        "ctx_read": {
            "read_modes": [
                {"name":"auto","description":"Predict best mode (predictor + adaptive policy)."},
                {"name":"full","description":"Full file content (cached)."},
                {"name":"map","description":"Deps + exports + key API signatures (TOON)."},
                {"name":"signatures","description":"API surface only."},
                {"name":"diff","description":"Changed lines since last read."},
                {"name":"aggressive","description":"Whitespace/comment stripping with safeguards."},
                {"name":"entropy","description":"Entropy/Jaccard-based extraction."},
                {"name":"task","description":"Task-aware compression (IB filter + graph context)."},
                {"name":"reference","description":"Header-only reference (lines/tokens), no content."},
                {"name":"lines:N-M","description":"Line-range extraction with line numbers."}
            ],
            "toon_header": {
                "deps": "  deps: a, b, c",
                "exports": "  exports: x, y",
                "api": "  API:\\n    <signature>"
            },
            "file_ref_format": "F<idx>=<short-path> <line-count>L",
            "compressed_hint": "[compressed — use mode=\"full\" for complete source]"
        },
        "stability": {
            "determinism": [
                "Sorted keys for manifests/exports.",
                "Stable ordering for ledgers and reports."
            ],
            "local_first": [
                "All files stored under NEBU_CTX_DATA_DIR by default.",
                "No raw prompts stored."
            ]
        }
    })
}

pub fn write_if_changed(path: &Path, content: &str) -> Result<(), String> {
    let existing = std::fs::read_to_string(path).ok();
    if existing.as_deref() == Some(content) {
        return Ok(());
    }
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)
            .map_err(|e| format!("create_dir_all {}: {e}", parent.display()))?;
    }
    std::fs::write(path, content).map_err(|e| format!("write {}: {e}", path.display()))
}
