//! ZK API endpoints.
//!
//! REST endpoints for zero-knowledge proof operations:
//! - Circuit compilation
//! - Proof generation
//! - Proof verification
//! - Trusted setup ceremonies

use axum::{
    extract::{Path, Query, State},
    routing::{get, post},
    Json, Router,
};
use serde::{Deserialize, Serialize};

use crate::{
    auth::{require_permission, Authenticated},
    error::ApiResult,
    response::{ApiResponse, PaginationParams},
    routes::AppState,
};

/// Build ZK routes.
pub fn router() -> Router<AppState> {
    Router::new()
        // Circuits
        .route("/circuits", get(list_circuits))
        .route("/circuits/compile", post(compile_circuit))
        .route("/circuits/:circuit_id", get(get_circuit))
        // Proofs - Groth16
        .route("/groth16/setup", post(groth16_setup))
        .route("/groth16/prove", post(groth16_prove))
        .route("/groth16/verify", post(groth16_verify))
        // Proofs - PLONK
        .route("/plonk/setup", post(plonk_setup))
        .route("/plonk/prove", post(plonk_prove))
        .route("/plonk/verify", post(plonk_verify))
        // Proofs - STARK
        .route("/stark/prove", post(stark_prove))
        .route("/stark/verify", post(stark_verify))
        // Recursive proofs
        .route("/recursive/prove", post(recursive_prove))
        .route("/recursive/aggregate", post(recursive_aggregate))
        .route("/recursive/verify", post(recursive_verify))
        // Ceremonies
        .route("/ceremonies", get(list_ceremonies))
        .route("/ceremonies", post(create_ceremony))
        .route("/ceremonies/:ceremony_id", get(get_ceremony))
        .route("/ceremonies/:ceremony_id/contribute", post(contribute))
}

// Types
#[derive(Debug, Serialize)]
pub struct Circuit {
    pub circuit_id: String,
    pub name: String,
    pub constraints: u64,
    pub public_inputs: u32,
    pub private_inputs: u32,
    pub outputs: u32,
}

#[derive(Debug, Deserialize)]
pub struct CompileCircuitRequest {
    pub code: String,
    pub language: String, // circom, noir, etc.
}

#[derive(Debug, Serialize)]
pub struct CompileCircuitResponse {
    pub circuit_id: String,
    pub constraints: u64,
    pub public_inputs: u32,
    pub private_inputs: u32,
    pub outputs: u32,
}

#[derive(Debug, Deserialize)]
pub struct ProveRequest {
    pub circuit_id: String,
    pub witness: serde_json::Value,
    pub proving_key: Option<String>,
}

#[derive(Debug, Serialize)]
pub struct ProofResponse {
    pub proof: String,
    pub public_signals: Vec<String>,
    pub proving_time_ms: u64,
}

#[derive(Debug, Deserialize)]
pub struct VerifyRequest {
    pub proof: String,
    pub public_signals: Vec<String>,
    pub verification_key: Option<String>,
}

#[derive(Debug, Serialize)]
pub struct VerifyResponse {
    pub valid: bool,
    pub verification_time_ms: u64,
}

#[derive(Debug, Serialize)]
pub struct SetupResponse {
    pub proving_key: String,
    pub verification_key: String,
}

#[derive(Debug, Serialize)]
pub struct Ceremony {
    pub ceremony_id: String,
    pub circuit_id: String,
    pub status: String,
    pub participant_count: u32,
    pub current_round: u32,
    pub created_at: String,
}

#[derive(Debug, Deserialize)]
pub struct CreateCeremonyRequest {
    pub circuit_id: String,
    pub min_participants: u32,
    pub max_participants: u32,
    pub round_duration: u32,
}

#[derive(Debug, Deserialize)]
pub struct ContributeRequest {
    pub entropy: String, // base64 encoded random bytes
}

// Handlers
async fn list_circuits(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Query(pagination): Query<PaginationParams>,
) -> ApiResult<Json<ApiResponse<Vec<Circuit>>>> {
    require_permission(&auth, "read")?;

    let circuits = vec![
        Circuit {
            circuit_id: "multiplier-v1".to_string(),
            name: "Multiplier".to_string(),
            constraints: 1,
            public_inputs: 1,
            private_inputs: 2,
            outputs: 1,
        },
    ];

    let meta = pagination.to_meta(circuits.len() as u64);
    Ok(Json(ApiResponse::success_paginated(circuits, meta)))
}

async fn compile_circuit(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<CompileCircuitRequest>,
) -> ApiResult<Json<ApiResponse<CompileCircuitResponse>>> {
    require_permission(&auth, "write")?;

    let response = CompileCircuitResponse {
        circuit_id: "new-circuit-123".to_string(),
        constraints: 100,
        public_inputs: 1,
        private_inputs: 2,
        outputs: 1,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn get_circuit(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(circuit_id): Path<String>,
) -> ApiResult<Json<ApiResponse<Circuit>>> {
    require_permission(&auth, "read")?;

    let circuit = Circuit {
        circuit_id,
        name: "Multiplier".to_string(),
        constraints: 1,
        public_inputs: 1,
        private_inputs: 2,
        outputs: 1,
    };

    Ok(Json(ApiResponse::success(circuit)))
}

async fn groth16_setup(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<SetupResponse>>> {
    require_permission(&auth, "write")?;

    let response = SetupResponse {
        proving_key: "pk_base64...".to_string(),
        verification_key: "vk_base64...".to_string(),
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn groth16_prove(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<ProveRequest>,
) -> ApiResult<Json<ApiResponse<ProofResponse>>> {
    require_permission(&auth, "write")?;

    let response = ProofResponse {
        proof: "proof_base64...".to_string(),
        public_signals: vec!["21".to_string()],
        proving_time_ms: 500,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn groth16_verify(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<VerifyRequest>,
) -> ApiResult<Json<ApiResponse<VerifyResponse>>> {
    require_permission(&auth, "read")?;

    let response = VerifyResponse {
        valid: true,
        verification_time_ms: 10,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn plonk_setup(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<SetupResponse>>> {
    require_permission(&auth, "write")?;

    let response = SetupResponse {
        proving_key: "plonk_pk_base64...".to_string(),
        verification_key: "plonk_vk_base64...".to_string(),
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn plonk_prove(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<ProveRequest>,
) -> ApiResult<Json<ApiResponse<ProofResponse>>> {
    require_permission(&auth, "write")?;

    let response = ProofResponse {
        proof: "plonk_proof_base64...".to_string(),
        public_signals: vec!["21".to_string()],
        proving_time_ms: 300,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn plonk_verify(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<VerifyRequest>,
) -> ApiResult<Json<ApiResponse<VerifyResponse>>> {
    require_permission(&auth, "read")?;

    let response = VerifyResponse {
        valid: true,
        verification_time_ms: 15,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn stark_prove(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<ProofResponse>>> {
    require_permission(&auth, "write")?;

    let response = ProofResponse {
        proof: "stark_proof_base64...".to_string(),
        public_signals: vec!["21".to_string()],
        proving_time_ms: 1000,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn stark_verify(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<VerifyRequest>,
) -> ApiResult<Json<ApiResponse<VerifyResponse>>> {
    require_permission(&auth, "read")?;

    let response = VerifyResponse {
        valid: true,
        verification_time_ms: 50,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn recursive_prove(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<ProofResponse>>> {
    require_permission(&auth, "write")?;

    let response = ProofResponse {
        proof: "recursive_proof...".to_string(),
        public_signals: vec![],
        proving_time_ms: 200,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn recursive_aggregate(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<serde_json::Value>>> {
    require_permission(&auth, "write")?;

    let response = serde_json::json!({
        "proof": "aggregated_proof...",
        "proofs_aggregated": 3,
        "recursion_depth": 1
    });

    Ok(Json(ApiResponse::success(response)))
}

async fn recursive_verify(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<serde_json::Value>,
) -> ApiResult<Json<ApiResponse<VerifyResponse>>> {
    require_permission(&auth, "read")?;

    let response = VerifyResponse {
        valid: true,
        verification_time_ms: 5,
    };

    Ok(Json(ApiResponse::success(response)))
}

async fn list_ceremonies(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Query(pagination): Query<PaginationParams>,
) -> ApiResult<Json<ApiResponse<Vec<Ceremony>>>> {
    require_permission(&auth, "read")?;

    let ceremonies = vec![];
    let meta = pagination.to_meta(0);
    Ok(Json(ApiResponse::success_paginated(ceremonies, meta)))
}

async fn create_ceremony(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Json(req): Json<CreateCeremonyRequest>,
) -> ApiResult<Json<ApiResponse<Ceremony>>> {
    require_permission(&auth, "write")?;

    let ceremony = Ceremony {
        ceremony_id: "ceremony_123".to_string(),
        circuit_id: req.circuit_id,
        status: "active".to_string(),
        participant_count: 0,
        current_round: 1,
        created_at: "2024-01-15T10:30:00Z".to_string(),
    };

    Ok(Json(ApiResponse::success(ceremony)))
}

async fn get_ceremony(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(ceremony_id): Path<String>,
) -> ApiResult<Json<ApiResponse<Ceremony>>> {
    require_permission(&auth, "read")?;

    let ceremony = Ceremony {
        ceremony_id,
        circuit_id: "multiplier-v1".to_string(),
        status: "active".to_string(),
        participant_count: 5,
        current_round: 1,
        created_at: "2024-01-15T10:30:00Z".to_string(),
    };

    Ok(Json(ApiResponse::success(ceremony)))
}

async fn contribute(
    State(state): State<AppState>,
    Authenticated(auth): Authenticated,
    Path(ceremony_id): Path<String>,
    Json(req): Json<ContributeRequest>,
) -> ApiResult<Json<ApiResponse<serde_json::Value>>> {
    require_permission(&auth, "write")?;

    let result = serde_json::json!({
        "contribution_id": "contrib_123",
        "position": 6,
        "hash": "sha256hash..."
    });

    Ok(Json(ApiResponse::success(result)))
}
