use axum::{extract::{Path, State}, Json};
use chrono::NaiveDate;
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};

use crate::auth::{audit, AuthUser};
use crate::config::{MAX_RANGE_YEARS, MAX_SYMBOLS};
use crate::error::{AppError, AppResult};
use crate::state::S;
use crate::util::{canonical_json, new_id, now_iso, sha256_hex};

/// Matches the fixed backend contract `Cx`; wired by State extractor in main.rs.
pub type Cx = State<S>;
const FIELDS: [&str; 6] = ["open", "high", "low", "close", "volume", "adj_factor"];


#[derive(Deserialize, Serialize, Clone)]
pub struct InstrumentReq {
    pub symbol: String,
    pub market: String,
    pub asset_type: String,
    pub name: Option<String>,
}

#[derive(Deserialize)]
pub struct DatasetRequest {
    /// Optional: SPEC/UI permit an absent or blank name; the backend then
    /// auto-generates a descriptive name and persists it.
    /// Optional: SPEC/UI permit an absent or blank name; the backend then
    /// auto-generates a descriptive name and persists it.
    #[serde(default)]
    pub name: Option<String>,
    pub instruments: Vec<InstrumentReq>,
    pub start_date: String,
    pub end_date: String,
    pub frequency: String,
    pub adjustment: String,
    pub fields: Vec<String>,
}

pub fn canonical_request_value(req: &DatasetRequest) -> Value {
    json!({
        "instruments": req.instruments.iter().map(|i| json!({
            "symbol": i.symbol, "market": i.market, "asset_type": i.asset_type,
            "name": i.name.clone(),
        })).collect::<Vec<_>>(),
        "start_date": req.start_date, "end_date": req.end_date,
        "frequency": req.frequency, "adjustment": req.adjustment, "fields": req.fields,
    })
}

pub fn validate_request(req: &DatasetRequest) -> AppResult<String> {
    if req.instruments.is_empty() || req.instruments.len() > MAX_SYMBOLS {
        return Err(AppError::bad("validation", format!("instruments must be 1-{} items", MAX_SYMBOLS)));
    }
    if req.frequency != "daily" { return Err(AppError::bad("validation", "only daily frequency is supported")); }
    if !matches!(req.adjustment.as_str(), "none" | "qfq" | "hfq") {
        return Err(AppError::bad("validation", "adjustment must be none|qfq|hfq"));
    }
    if req.fields.is_empty() { return Err(AppError::bad("validation", "fields must not be empty")); }
    for f in &req.fields {
        if !FIELDS.contains(&f.as_str()) { return Err(AppError::bad("validation", format!("unsupported field: {f}"))); }
    }
    let mut seen = std::collections::HashSet::new();
    for i in &req.instruments {
        if i.symbol.trim().is_empty() || i.market.trim().is_empty() {
            return Err(AppError::bad("validation", "each instrument needs a symbol and a market"));
        }
        if !matches!(i.asset_type.as_str(), "stock" | "etf" | "index") {
            return Err(AppError::bad("validation", "asset_type must be stock|etf|index"));
        }
        if i.asset_type == "index" && req.adjustment != "none" {
            return Err(AppError::bad("validation", "index instruments support adjustment 'none' only (explicit restriction, no factors)"));
        }
        if !seen.insert(format!("{}|{}|{}", i.market, i.asset_type, i.symbol)) {
            return Err(AppError::bad("validation", "duplicate instrument in request"));
        }
    }
    let sd = NaiveDate::parse_from_str(&req.start_date, "%Y-%m-%d").map_err(|_| AppError::bad("validation", "start_date must be YYYY-MM-DD"))?;
    let ed = NaiveDate::parse_from_str(&req.end_date, "%Y-%m-%d").map_err(|_| AppError::bad("validation", "end_date must be YYYY-MM-DD"))?;
    if ed < sd { return Err(AppError::bad("validation", "end_date must not precede start_date")); }
    if (ed - sd).num_days() > MAX_RANGE_YEARS * 366 {
        return Err(AppError::bad("validation", "range exceeds maximum of 15 years"));
    }
    Ok(sha256_hex(canonical_json(&canonical_request_value(req)).as_bytes()))
}

/// Full stored manifest JSON -> client copy without host/internal paths.
pub fn client_manifest(m: &Value) -> Value {
    let mut o = m.clone();
    o.as_object_mut().map(|m| m.remove("preview"));
    if let Some(objs) = o.get_mut("objects").and_then(|v| v.as_array_mut()) {
        for obj in objs.iter_mut() {
            if let Some(map) = obj.as_object_mut() {
                map.remove("path");
            }
        }
    }
    o
}

fn row_dataset(r: &rusqlite::Row) -> rusqlite::Result<Value> {
    let manifest: Option<String> = r.get(6)?;
    let manifest_v: Value = manifest.and_then(|m| serde_json::from_str::<Value>(&m).ok()).unwrap_or(Value::Null);
    // The stored canonical request is persisted as a JSON string; clients get an object.
    let request_s: String = r.get(2)?;
    let request_v: Value = serde_json::from_str::<Value>(&request_s)
        .map_err(|_| rusqlite::Error::InvalidColumnType(2, "dataset request".into(), rusqlite::types::Type::Text))?;
    Ok(json!({
        "id": r.get::<_, String>(0)?,
        "name": r.get::<_, String>(1)?,
        "request": request_v,
        "status": r.get::<_, String>(3)?,
        "error": r.get::<_, Option<String>>(4)?,
        "cache_hit": r.get::<_, Option<i64>>(5)?.map(|v| v != 0),
        "manifest": if manifest_v.is_null() { Value::Null } else { client_manifest(&manifest_v) },
        "warnings": manifest_v.get("warnings").cloned().unwrap_or(json!([])),
        "manifest_hash": manifest_v.get("hash").cloned().unwrap_or(Value::Null),
        "created_at": r.get::<_, String>(7)?,
        "updated_at": r.get::<_, String>(8)?,
    }))
}

pub async fn assert_owned(cx: &Cx, user_id: &str, dataset_id: &str) -> AppResult<()> {
    let found: Option<String> = cx.with_db(|db| {
        db.query_row("SELECT user_id FROM datasets WHERE id=?1", [dataset_id], |r| r.get(0)).ok()
    }).await;
    match found {
        Some(o) if o == user_id => Ok(()),
        _ => Err(AppError::not_found("dataset not found")),
    }
}

async fn query_dataset(cx: &Cx, sql: &str, dataset_id: &str) -> AppResult<Value> {
    cx.with_db(move |db| {
        db.query_row(sql, [dataset_id], row_dataset)
            .map_err(|_| AppError::not_found("dataset not found"))
    }).await
}

const LIST_SQL: &str = "SELECT id,name,request,status,error,cache_hit,manifest,created_at,updated_at FROM datasets WHERE user_id=?1 ORDER BY created_at DESC LIMIT 200";

pub async fn list(cx: Cx, auth: AuthUser) -> AppResult<Json<Value>> {
    let items: Vec<Value> = cx.with_db(|db| {
        let mut st = db.prepare(LIST_SQL)?;
        let mut rows = st.query([auth.id.clone()])?;
        let mut out = Vec::new();
        while let Some(r) = rows.next()? { out.push(row_dataset(r)?); }
        Ok::<_, AppError>(out)
    }).await?;
    Ok(Json(json!({ "items": items })))
}

pub async fn get(cx: Cx, auth: AuthUser, Path(id): Path<String>) -> AppResult<Json<Value>> {
    assert_owned(&cx, &auth.id, &id).await?;
    let v = query_dataset(&cx, "SELECT id,name,request,status,error,cache_hit,manifest,created_at,updated_at FROM datasets WHERE id=?1", &id).await?;
    Ok(Json(v))
}

/// Load the stored worker manifest (with internal paths) of a ready dataset.
pub async fn load_manifest(cx: &Cx, dataset_id: &str) -> AppResult<Value> {
    let m: String = cx.with_db(|db| {
        db.query_row("SELECT manifest FROM datasets WHERE id=?1 AND status='ready'", [dataset_id], |r| r.get(0))
            .map_err(|_| AppError::conflict("dataset_not_ready", "dataset not ready"))
    }).await?;
    serde_json::from_str(&m).map_err(|e| AppError::internal(format!("manifest corrupt: {e}")))
}

pub async fn create(cx: Cx, auth: AuthUser, body: Option<Json<DatasetRequest>>) -> AppResult<(axum::http::StatusCode, Json<Value>)> {
    let Json(r) = body.ok_or_else(|| AppError::bad("invalid_body", "JSON body required"))?;
    // Frontend sends name: optional/empty; default is an auto-generated descriptive name.
    let name = if r.name.as_deref().map(|n| n.trim().is_empty()).unwrap_or(true) {
        // Frontend allows an empty name to auto-generate: instruments + range.
        let syms: Vec<String> = r.instruments.iter().map(|i| i.symbol.clone()).collect();
        format!("{} · {} ~ {}", syms.join(","), r.start_date, r.end_date)
    } else {
        r.name.as_deref().unwrap_or_default().trim().to_string()
    };
    if name.len() > 200 { return Err(AppError::bad("validation", "name required (max 200)")); }
    let _key = validate_request(&r)?;
    let stored_request = canonical_request_value(&r);
    let id = new_id();
    let ts = now_iso();
    let uid = auth.id.clone();
    cx.with_db(|db| -> AppResult<()> {
        db.execute("INSERT INTO datasets (id,user_id,name,request,status,cache_hit,created_at,updated_at) VALUES (?1,?2,?3,?4,'pending',0,?5,?5)",
            rusqlite::params![&id, &uid, &name, stored_request.to_string(), &ts])?;
        Ok(())
    }).await?;
    audit(&cx, Some(&auth.id), "dataset_create", &id, "ok").await;
    let v = query_dataset(&cx, "SELECT id,name,request,status,error,cache_hit,manifest,created_at,updated_at FROM datasets WHERE id=?1", &id).await?;
    Ok((axum::http::StatusCode::ACCEPTED, Json(v)))
}

pub async fn preview(cx: Cx, auth: AuthUser, Path(id): Path<String>) -> AppResult<Json<Value>> {
    assert_owned(&cx, &auth.id, &id).await?;
    let m = load_manifest(&cx, &id).await?;
    let p = m.get("preview").cloned().unwrap_or(Value::Null);
    if p.is_null() { return Err(AppError::not_found("preview not available yet")); }
    Ok(Json(p))
}


#[cfg(test)]
mod tests {
    use super::*;

    fn req() -> DatasetRequest {
        serde_json::from_value(json!({
            "name": "t", "instruments": [{"symbol": "600000", "market": "cn", "asset_type": "stock", "name": "浦发银行"}],
            "start_date": "2024-01-01", "end_date": "2024-06-30",
            "frequency": "daily", "adjustment": "none", "fields": ["open","high","low","close","volume"]
        })).unwrap()
    }

    #[test]
    fn validate_rejects_unsupported() {
        assert_eq!(validate_request(&req()).unwrap().len(), 64);
        let mut r = req(); r.frequency = "hourly".into();
        assert_eq!(validate_request(&r).unwrap_err().code, "validation");
        let mut r = req(); r.adjustment = "qfq".into(); r.instruments[0].asset_type = "index".into();
        assert_eq!(validate_request(&r).unwrap_err().code, "validation", "index+adjustment must be explicit rejections");
        let mut r = req(); r.instruments.push(r.instruments[0].clone());
        assert_eq!(validate_request(&r).unwrap_err().code, "validation", "duplicate instruments rejected");
    }

    #[test]
    fn cache_key_is_stable_and_shared_regardless_of_display_name() {
        let other = { let mut o = req(); o.name = Some("别的名字".to_string()); o };
        assert_eq!(canonical_request_value(&req()), canonical_request_value(&other));
        assert_eq!(validate_request(&req()).unwrap(), validate_request(&other).unwrap());
    }

    #[test]
    fn client_manifest_strips_internal_paths_and_preview() {
        let m = json!({
            "hash": "h", "warnings": [], "preview": {"rows": [1]},
            "objects": [{"instrument": {"symbol": "SH#600000"}, "path": "objects/ab/ab12.csv"}]
        });
        let c = client_manifest(&m);
        assert!(serde_json::to_string(&c).unwrap().find("objects/ab").is_none(), "host paths must not leak");
        assert_eq!(c.get("hash"), Some(&json!("h")));
    }
}