use actix_web::dev::{ServiceFactory, ServiceRequest};
use actix_web::{App, HttpRequest, HttpResponse, Responder, web};
use chrono::Utc;
use serde::{Deserialize, Serialize};
use std::sync::Mutex;

use crate::data::Claims;
use crate::database::models::{Entity, EntityFact, EntityPhotoLink, InsertEntityFact};
use crate::database::{
    EntityFilter, EntityPatch, FactFilter, FactPatch, KnowledgeDao, PersonaFilter, RecentActivity,
};
use crate::personas::PersonaDaoData;

/// Resolve the `X-Persona-Id` header into a `PersonaFilter`. Missing
/// header → `'default'`. If the persona has `include_all_memories=true`,
/// returns `PersonaFilter::All` so reads see the full hive-mind pool.
/// On JWT-parse failure (sub is not a numeric user_id) the resolver
/// falls through to user_id=1 — the operator convention for service
/// tokens — preserving the historical baseline view. Same fallback
/// applies on any persona-lookup error.
fn resolve_persona_filter(
    req: &HttpRequest,
    claims: &Claims,
    persona_dao: &PersonaDaoData,
) -> PersonaFilter {
    let pid = req
        .headers()
        .get("X-Persona-Id")
        .and_then(|v| v.to_str().ok())
        .map(|s| s.to_string())
        .unwrap_or_else(|| "default".to_string());

    let uid = claims.sub.parse::<i32>().unwrap_or(1);

    let cx = opentelemetry::Context::current();
    let mut dao = persona_dao.lock().expect("Unable to lock PersonaDao");
    match dao.get_persona(&cx, uid, &pid) {
        Ok(Some(p)) if p.include_all_memories => PersonaFilter::All { user_id: uid },
        _ => PersonaFilter::Single {
            user_id: uid,
            persona_id: pid,
        },
    }
}

// ---------------------------------------------------------------------------
// Request / Response types
// ---------------------------------------------------------------------------

#[derive(Serialize)]
pub struct EntitySummary {
    pub id: i32,
    pub name: String,
    pub entity_type: String,
    pub description: String,
    pub confidence: f32,
    pub status: String,
    pub created_at: i64,
    pub updated_at: i64,
}

impl From<Entity> for EntitySummary {
    fn from(e: Entity) -> Self {
        EntitySummary {
            id: e.id,
            name: e.name,
            entity_type: e.entity_type,
            description: e.description,
            confidence: e.confidence,
            status: e.status,
            created_at: e.created_at,
            updated_at: e.updated_at,
        }
    }
}

#[derive(Serialize)]
pub struct EntityListResponse {
    pub entities: Vec<EntitySummary>,
    pub total: i64,
    pub limit: i64,
    pub offset: i64,
}

#[derive(Serialize)]
pub struct FactDetail {
    pub id: i32,
    pub predicate: String,
    pub object_entity_id: Option<i32>,
    pub object_entity_name: Option<String>,
    pub object_value: Option<String>,
    pub confidence: f32,
    pub status: String,
    pub source_photo: Option<String>,
    pub source_insight_id: Option<i32>,
    pub created_at: i64,
}

#[derive(Serialize)]
pub struct PhotoLinkDetail {
    pub file_path: String,
    pub role: String,
}

impl From<EntityPhotoLink> for PhotoLinkDetail {
    fn from(l: EntityPhotoLink) -> Self {
        PhotoLinkDetail {
            file_path: l.file_path,
            role: l.role,
        }
    }
}

#[derive(Serialize)]
pub struct EntityDetailResponse {
    pub id: i32,
    pub name: String,
    pub entity_type: String,
    pub description: String,
    pub confidence: f32,
    pub status: String,
    pub created_at: i64,
    pub updated_at: i64,
    pub facts: Vec<FactDetail>,
    pub photo_links: Vec<PhotoLinkDetail>,
}

#[derive(Serialize)]
pub struct FactSummary {
    pub id: i32,
    pub subject_entity_id: i32,
    pub subject_entity_name: Option<String>,
    pub predicate: String,
    pub object_entity_id: Option<i32>,
    pub object_entity_name: Option<String>,
    pub object_value: Option<String>,
    pub confidence: f32,
    pub status: String,
    pub source_photo: Option<String>,
    pub source_insight_id: Option<i32>,
    pub created_at: i64,
}

#[derive(Serialize)]
pub struct FactListResponse {
    pub facts: Vec<FactSummary>,
    pub total: i64,
    pub limit: i64,
    pub offset: i64,
}

#[derive(Deserialize)]
pub struct MergeRequest {
    pub source_id: i32,
    pub target_id: i32,
}

#[derive(Serialize)]
pub struct MergeResponse {
    pub merged_entity_id: i32,
    pub deleted_entity_id: i32,
    pub facts_transferred: i64,
    pub links_transferred: i64,
}

#[derive(Deserialize)]
pub struct EntityPatchRequest {
    pub name: Option<String>,
    pub description: Option<String>,
    pub status: Option<String>,
    pub confidence: Option<f32>,
}

#[derive(Deserialize)]
pub struct FactPatchRequest {
    pub predicate: Option<String>,
    pub object_value: Option<String>,
    pub status: Option<String>,
    pub confidence: Option<f32>,
}

#[derive(Deserialize)]
pub struct FactCreateRequest {
    pub subject_entity_id: i32,
    pub predicate: String,
    pub object_entity_id: Option<i32>,
    pub object_value: Option<String>,
    pub source_photo: Option<String>,
    pub confidence: Option<f32>,
}

#[derive(Deserialize)]
pub struct EntityListQuery {
    #[serde(rename = "type")]
    pub entity_type: Option<String>,
    pub status: Option<String>,
    pub search: Option<String>,
    pub limit: Option<i64>,
    pub offset: Option<i64>,
}

#[derive(Deserialize)]
pub struct FactListQuery {
    pub entity_id: Option<i32>,
    pub status: Option<String>,
    pub predicate: Option<String>,
    pub limit: Option<i64>,
    pub offset: Option<i64>,
}

#[derive(Deserialize)]
pub struct RecentQuery {
    pub since: Option<i64>,
    pub limit: Option<i64>,
}

// ---------------------------------------------------------------------------
// Service registration
// ---------------------------------------------------------------------------

pub fn add_knowledge_services<T, D: KnowledgeDao + 'static>(app: App<T>) -> App<T>
where
    T: ServiceFactory<ServiceRequest, Config = (), Error = actix_web::Error, InitError = ()>,
{
    app.service(
        web::scope("/knowledge")
            .service(web::resource("/entities").route(web::get().to(list_entities::<D>)))
            .service(web::resource("/entities/merge").route(web::post().to(merge_entities::<D>)))
            .service(
                web::resource("/entities/{id}")
                    .route(web::get().to(get_entity::<D>))
                    .route(web::patch().to(patch_entity::<D>))
                    .route(web::delete().to(delete_entity::<D>)),
            )
            .service(
                web::resource("/facts")
                    .route(web::get().to(list_facts::<D>))
                    .route(web::post().to(create_fact::<D>)),
            )
            .service(
                web::resource("/facts/{id}")
                    .route(web::patch().to(patch_fact::<D>))
                    .route(web::delete().to(delete_fact::<D>)),
            )
            .service(web::resource("/recent").route(web::get().to(get_recent::<D>))),
    )
}

// ---------------------------------------------------------------------------
// Handlers
// ---------------------------------------------------------------------------

async fn list_entities<D: KnowledgeDao + 'static>(
    _claims: Claims,
    query: web::Query<EntityListQuery>,
    dao: web::Data<Mutex<D>>,
) -> impl Responder {
    let limit = query.limit.unwrap_or(50).min(200);
    let offset = query.offset.unwrap_or(0);

    let status_filter = match query.status.as_deref() {
        None | Some("active") => Some("active".to_string()),
        Some("all") => None,
        Some(s) => Some(s.to_string()),
    };

    let filter = EntityFilter {
        entity_type: query.entity_type.clone(),
        status: status_filter,
        search: query.search.clone(),
        limit,
        offset,
    };

    let cx = opentelemetry::Context::current();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");
    match dao.list_entities(&cx, filter) {
        Ok((entities, total)) => {
            let summaries: Vec<EntitySummary> =
                entities.into_iter().map(EntitySummary::from).collect();
            HttpResponse::Ok().json(EntityListResponse {
                entities: summaries,
                total,
                limit,
                offset,
            })
        }
        Err(e) => {
            log::error!("list_entities error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}

async fn get_entity<D: KnowledgeDao + 'static>(
    req: HttpRequest,
    claims: Claims,
    id: web::Path<i32>,
    dao: web::Data<Mutex<D>>,
    persona_dao: PersonaDaoData,
) -> impl Responder {
    let persona = resolve_persona_filter(&req, &claims, &persona_dao);
    let cx = opentelemetry::Context::current();
    let entity_id = id.into_inner();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");

    let entity = match dao.get_entity_by_id(&cx, entity_id) {
        Ok(Some(e)) => e,
        Ok(None) => {
            return HttpResponse::NotFound().json(serde_json::json!({"error": "Entity not found"}));
        }
        Err(e) => {
            log::error!("get_entity error: {:?}", e);
            return HttpResponse::InternalServerError()
                .json(serde_json::json!({"error": "Database error"}));
        }
    };

    // Fetch all facts (all statuses for audit), scoped to the active persona.
    let raw_facts: Vec<EntityFact> = match dao.get_facts_for_entity(&cx, entity_id, &persona) {
        Ok(f) => f,
        Err(e) => {
            log::error!("get_facts_for_entity error: {:?}", e);
            return HttpResponse::InternalServerError()
                .json(serde_json::json!({"error": "Database error"}));
        }
    };

    // Resolve object entity names
    let mut facts = Vec::with_capacity(raw_facts.len());
    for f in raw_facts {
        let object_entity_name = if let Some(oid) = f.object_entity_id {
            dao.get_entity_by_id(&cx, oid)
                .ok()
                .flatten()
                .map(|e| e.name)
        } else {
            None
        };
        facts.push(FactDetail {
            id: f.id,
            predicate: f.predicate,
            object_entity_id: f.object_entity_id,
            object_entity_name,
            object_value: f.object_value,
            confidence: f.confidence,
            status: f.status,
            source_photo: f.source_photo,
            source_insight_id: f.source_insight_id,
            created_at: f.created_at,
        });
    }

    // Fetch photo links
    let photo_links: Vec<PhotoLinkDetail> = match dao.get_links_for_entity(&cx, entity_id) {
        Ok(links) => links.into_iter().map(PhotoLinkDetail::from).collect(),
        Err(e) => {
            log::error!("get_links_for_entity error: {:?}", e);
            return HttpResponse::InternalServerError()
                .json(serde_json::json!({"error": "Database error"}));
        }
    };

    HttpResponse::Ok().json(EntityDetailResponse {
        id: entity.id,
        name: entity.name,
        entity_type: entity.entity_type,
        description: entity.description,
        confidence: entity.confidence,
        status: entity.status,
        created_at: entity.created_at,
        updated_at: entity.updated_at,
        facts,
        photo_links,
    })
}

async fn patch_entity<D: KnowledgeDao + 'static>(
    _claims: Claims,
    id: web::Path<i32>,
    body: web::Json<EntityPatchRequest>,
    dao: web::Data<Mutex<D>>,
) -> impl Responder {
    let cx = opentelemetry::Context::current();
    let entity_id = id.into_inner();
    let patch = EntityPatch {
        name: body.name.clone(),
        description: body.description.clone(),
        status: body.status.clone(),
        confidence: body.confidence,
    };

    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");
    match dao.update_entity(&cx, entity_id, patch) {
        Ok(Some(entity)) => HttpResponse::Ok().json(EntitySummary::from(entity)),
        Ok(None) => HttpResponse::NotFound().json(serde_json::json!({"error": "Entity not found"})),
        Err(e) => {
            log::error!("patch_entity error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}

async fn delete_entity<D: KnowledgeDao + 'static>(
    _claims: Claims,
    id: web::Path<i32>,
    dao: web::Data<Mutex<D>>,
) -> impl Responder {
    let cx = opentelemetry::Context::current();
    let entity_id = id.into_inner();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");

    // Verify entity exists before deleting
    match dao.get_entity_by_id(&cx, entity_id) {
        Ok(None) => {
            return HttpResponse::NotFound().json(serde_json::json!({"error": "Entity not found"}));
        }
        Err(e) => {
            log::error!("delete_entity lookup error: {:?}", e);
            return HttpResponse::InternalServerError()
                .json(serde_json::json!({"error": "Database error"}));
        }
        Ok(Some(_)) => {}
    }

    match dao.delete_entity(&cx, entity_id) {
        Ok(()) => HttpResponse::NoContent().finish(),
        Err(e) => {
            log::error!("delete_entity error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}

async fn merge_entities<D: KnowledgeDao + 'static>(
    _claims: Claims,
    body: web::Json<MergeRequest>,
    dao: web::Data<Mutex<D>>,
) -> impl Responder {
    if body.source_id == body.target_id {
        return HttpResponse::BadRequest()
            .json(serde_json::json!({"error": "source_id and target_id must be different"}));
    }

    let cx = opentelemetry::Context::current();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");

    // Verify both entities exist
    for id in [body.source_id, body.target_id] {
        match dao.get_entity_by_id(&cx, id) {
            Ok(None) => {
                return HttpResponse::BadRequest()
                    .json(serde_json::json!({"error": format!("Entity {} not found", id)}));
            }
            Err(e) => {
                log::error!("merge_entities lookup error: {:?}", e);
                return HttpResponse::InternalServerError()
                    .json(serde_json::json!({"error": "Database error"}));
            }
            Ok(Some(_)) => {}
        }
    }

    match dao.merge_entities(&cx, body.source_id, body.target_id) {
        Ok((facts_transferred, links_transferred)) => HttpResponse::Ok().json(MergeResponse {
            merged_entity_id: body.target_id,
            deleted_entity_id: body.source_id,
            facts_transferred,
            links_transferred,
        }),
        Err(e) => {
            log::error!("merge_entities error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}

async fn list_facts<D: KnowledgeDao + 'static>(
    req: HttpRequest,
    claims: Claims,
    query: web::Query<FactListQuery>,
    dao: web::Data<Mutex<D>>,
    persona_dao: PersonaDaoData,
) -> impl Responder {
    let limit = query.limit.unwrap_or(50).min(200);
    let offset = query.offset.unwrap_or(0);

    let status_filter = match query.status.as_deref() {
        None | Some("active") => Some("active".to_string()),
        Some("all") => None,
        Some(s) => Some(s.to_string()),
    };
    let persona = resolve_persona_filter(&req, &claims, &persona_dao);

    let filter = FactFilter {
        entity_id: query.entity_id,
        status: status_filter,
        predicate: query.predicate.clone(),
        persona,
        limit,
        offset,
    };

    let cx = opentelemetry::Context::current();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");
    match dao.list_facts(&cx, filter) {
        Ok((facts, total)) => {
            let mut summaries = Vec::with_capacity(facts.len());
            for f in facts {
                let subject_entity_name = dao
                    .get_entity_by_id(&cx, f.subject_entity_id)
                    .ok()
                    .flatten()
                    .map(|e| e.name);
                let object_entity_name = if let Some(oid) = f.object_entity_id {
                    dao.get_entity_by_id(&cx, oid)
                        .ok()
                        .flatten()
                        .map(|e| e.name)
                } else {
                    None
                };
                summaries.push(FactSummary {
                    id: f.id,
                    subject_entity_id: f.subject_entity_id,
                    subject_entity_name,
                    predicate: f.predicate,
                    object_entity_id: f.object_entity_id,
                    object_entity_name,
                    object_value: f.object_value,
                    confidence: f.confidence,
                    status: f.status,
                    source_photo: f.source_photo,
                    source_insight_id: f.source_insight_id,
                    created_at: f.created_at,
                });
            }
            HttpResponse::Ok().json(FactListResponse {
                facts: summaries,
                total,
                limit,
                offset,
            })
        }
        Err(e) => {
            log::error!("list_facts error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}

async fn create_fact<D: KnowledgeDao + 'static>(
    req: HttpRequest,
    claims: Claims,
    body: web::Json<FactCreateRequest>,
    dao: web::Data<Mutex<D>>,
    persona_dao: PersonaDaoData,
) -> impl Responder {
    if body.object_entity_id.is_none() && body.object_value.is_none() {
        return HttpResponse::BadRequest().json(serde_json::json!({
            "error": "object_entity_id or object_value is required"
        }));
    }
    if body.predicate.trim().is_empty() {
        return HttpResponse::BadRequest()
            .json(serde_json::json!({"error": "predicate must not be empty"}));
    }

    // Persona scoping: facts are written under the active single persona.
    // PersonaFilter::All is read-only ("hive-mind" view); callers should
    // pin a specific persona for writes via X-Persona-Id.
    let persona = resolve_persona_filter(&req, &claims, &persona_dao);
    let (user_id, persona_id) = match &persona {
        PersonaFilter::Single { user_id, persona_id } => (*user_id, persona_id.clone()),
        PersonaFilter::All { user_id } => (*user_id, "default".to_string()),
    };

    let cx = opentelemetry::Context::current();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");

    // Verify subject entity exists.
    match dao.get_entity_by_id(&cx, body.subject_entity_id) {
        Ok(None) => {
            return HttpResponse::BadRequest().json(serde_json::json!({
                "error": format!("Subject entity {} not found", body.subject_entity_id)
            }));
        }
        Err(e) => {
            log::error!("create_fact subject lookup error: {:?}", e);
            return HttpResponse::InternalServerError()
                .json(serde_json::json!({"error": "Database error"}));
        }
        Ok(Some(_)) => {}
    }

    // Optional object entity validation when supplied.
    if let Some(oid) = body.object_entity_id {
        match dao.get_entity_by_id(&cx, oid) {
            Ok(None) => {
                return HttpResponse::BadRequest().json(serde_json::json!({
                    "error": format!("Object entity {} not found", oid)
                }));
            }
            Err(e) => {
                log::error!("create_fact object lookup error: {:?}", e);
                return HttpResponse::InternalServerError()
                    .json(serde_json::json!({"error": "Database error"}));
            }
            Ok(Some(_)) => {}
        }
    }

    let now = Utc::now().timestamp();
    let confidence = body.confidence.unwrap_or(0.6).clamp(0.0, 0.95);

    let insert = InsertEntityFact {
        subject_entity_id: body.subject_entity_id,
        predicate: body.predicate.trim().to_string(),
        object_entity_id: body.object_entity_id,
        object_value: body.object_value.clone(),
        source_photo: body.source_photo.clone(),
        source_insight_id: None,
        confidence,
        status: "active".to_string(),
        created_at: now,
        persona_id,
        user_id,
    };

    match dao.upsert_fact(&cx, insert) {
        Ok((fact, is_new)) => {
            let status = if is_new {
                actix_web::http::StatusCode::CREATED
            } else {
                actix_web::http::StatusCode::OK
            };
            HttpResponse::build(status).json(fact)
        }
        Err(e) => {
            log::error!("create_fact upsert error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}

async fn patch_fact<D: KnowledgeDao + 'static>(
    _claims: Claims,
    id: web::Path<i32>,
    body: web::Json<FactPatchRequest>,
    dao: web::Data<Mutex<D>>,
) -> impl Responder {
    let cx = opentelemetry::Context::current();
    let fact_id = id.into_inner();
    let patch = FactPatch {
        predicate: body.predicate.clone(),
        object_value: body.object_value.clone(),
        status: body.status.clone(),
        confidence: body.confidence,
    };

    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");
    match dao.update_fact(&cx, fact_id, patch) {
        Ok(Some(fact)) => HttpResponse::Ok().json(fact),
        Ok(None) => HttpResponse::NotFound().json(serde_json::json!({"error": "Fact not found"})),
        Err(e) => {
            log::error!("patch_fact error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}

async fn delete_fact<D: KnowledgeDao + 'static>(
    _claims: Claims,
    id: web::Path<i32>,
    dao: web::Data<Mutex<D>>,
) -> impl Responder {
    let cx = opentelemetry::Context::current();
    let fact_id = id.into_inner();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");
    match dao.delete_fact(&cx, fact_id) {
        Ok(()) => HttpResponse::NoContent().finish(),
        Err(e) => {
            log::warn!("delete_fact({}) error: {:?}", fact_id, e);
            HttpResponse::NotFound().json(serde_json::json!({"error": "Fact not found"}))
        }
    }
}

async fn get_recent<D: KnowledgeDao + 'static>(
    req: HttpRequest,
    claims: Claims,
    query: web::Query<RecentQuery>,
    dao: web::Data<Mutex<D>>,
    persona_dao: PersonaDaoData,
) -> impl Responder {
    let since = query
        .since
        .unwrap_or_else(|| Utc::now().timestamp() - 86400);
    let limit = query.limit.unwrap_or(20).min(100);

    let persona = resolve_persona_filter(&req, &claims, &persona_dao);
    let cx = opentelemetry::Context::current();
    let mut dao = dao.lock().expect("Unable to lock KnowledgeDao");
    match dao.get_recent_activity(&cx, since, limit, &persona) {
        Ok(RecentActivity { entities, facts }) => {
            let entity_summaries: Vec<EntitySummary> =
                entities.into_iter().map(EntitySummary::from).collect();
            HttpResponse::Ok().json(serde_json::json!({
                "entities": entity_summaries,
                "facts": facts
            }))
        }
        Err(e) => {
            log::error!("get_recent error: {:?}", e);
            HttpResponse::InternalServerError().json(serde_json::json!({"error": "Database error"}))
        }
    }
}