use crate::AppState;
use axum::{
    extract::{Path, Query, State},
    http::StatusCode,
    response::IntoResponse,
    routing::get,
    Json, Router,
};
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use sqlx::Row;
use uuid::Uuid;

pub fn router() -> Router<AppState> {
    Router::new()
        .route("/", get(list_designations).post(create_designation))
        .route("/{id}", get(get_designation).patch(update_designation).delete(delete_designation))
}

#[derive(Deserialize)]
struct ListQuery {
    q: Option<String>,
    status: Option<String>,
    department_id: Option<Uuid>,
    page: Option<i64>,
    per_page: Option<i64>,
    limit: Option<i64>,
}

#[derive(Serialize)]
struct DesignationRow {
    id: Uuid,
    name: String,
    code: Option<String>,
    department_id: Option<Uuid>,
    department_name: Option<String>,
    description: Option<String>,
    level: Option<String>,
    can_manage_team: bool,
    can_approve: bool,
    is_active: bool,
    status: String,
    total_employees: i64,
    created_at: DateTime<Utc>,
    updated_at: DateTime<Utc>,
}

#[derive(Serialize)]
struct ListResponse {
    designations: Vec<DesignationRow>,
    total: i64,
    page: i64,
    per_page: i64,
}

#[derive(Deserialize)]
struct CreateDesignationPayload {
    name: String,
    code: Option<String>,
    department_id: Option<Uuid>,
    description: Option<String>,
    level: Option<String>,
    can_manage_team: Option<bool>,
    can_approve: Option<bool>,
    is_active: Option<bool>,
    status: Option<String>,
}

#[derive(Deserialize)]
struct UpdateDesignationPayload {
    name: Option<String>,
    code: Option<String>,
    department_id: Option<Uuid>,
    description: Option<String>,
    level: Option<String>,
    can_manage_team: Option<bool>,
    can_approve: Option<bool>,
    is_active: Option<bool>,
    status: Option<String>,
}

fn derive_is_active(status: &Option<String>, is_active: Option<bool>, current: bool) -> bool {
    if let Some(active) = is_active {
        return active;
    }
    match status.as_deref().unwrap_or_default().to_ascii_uppercase().as_str() {
        "ACTIVE" => true,
        "INACTIVE" => false,
        _ => current,
    }
}

async fn list_designations(
    State(state): State<AppState>,
    Query(params): Query<ListQuery>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let page = params.page.unwrap_or(1).max(1);
    let per_page = params.per_page.or(params.limit).unwrap_or(20).clamp(1, 100);
    let offset = (page - 1) * per_page;
    let search = params.q.unwrap_or_default().to_lowercase();
    let status = params.status.unwrap_or_default().to_lowercase();

    let rows = sqlx::query(
        r#"
        SELECT
            des.id,
            des.name,
            des.code,
            des.department_id,
            dep.name AS department_name,
            des.description,
            des.level,
            des.can_manage_team,
            des.can_approve,
            des.is_active,
            des.created_at,
            des.updated_at,
            COUNT(e.id) AS total_employees
        FROM designations des
        LEFT JOIN departments dep ON dep.id = des.department_id
        LEFT JOIN employees e ON e.designation_id = des.id
        WHERE ($1 = '' OR LOWER(des.name) LIKE '%' || $1 || '%' OR LOWER(COALESCE(des.code, '')) LIKE '%' || $1 || '%')
          AND (
            $2 = ''
            OR ($2 = 'active' AND des.is_active = true)
            OR ($2 = 'inactive' AND des.is_active = false)
          )
          AND ($3::uuid IS NULL OR des.department_id = $3)
        GROUP BY des.id, dep.name
        ORDER BY des.created_at DESC
        LIMIT $4 OFFSET $5
        "#,
    )
    .bind(&search)
    .bind(&status)
    .bind(params.department_id)
    .bind(per_page)
    .bind(offset)
    .fetch_all(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;

    let designations = rows
        .into_iter()
        .map(|row| DesignationRow {
            id: row.get("id"),
            name: row.get("name"),
            code: row.get("code"),
            department_id: row.get("department_id"),
            department_name: row.get("department_name"),
            description: row.get("description"),
            level: row.get("level"),
            can_manage_team: row.get("can_manage_team"),
            can_approve: row.get("can_approve"),
            is_active: row.get("is_active"),
            status: if row.get::<bool, _>("is_active") {
                "ACTIVE".to_string()
            } else {
                "INACTIVE".to_string()
            },
            total_employees: row.get("total_employees"),
            created_at: row.get("created_at"),
            updated_at: row.get("updated_at"),
        })
        .collect();

    let total: i64 = sqlx::query_scalar::<_, Option<i64>>(
        r#"
        SELECT COUNT(*) FROM designations des
        WHERE ($1 = '' OR LOWER(des.name) LIKE '%' || $1 || '%' OR LOWER(COALESCE(des.code, '')) LIKE '%' || $1 || '%')
          AND (
            $2 = ''
            OR ($2 = 'active' AND des.is_active = true)
            OR ($2 = 'inactive' AND des.is_active = false)
          )
          AND ($3::uuid IS NULL OR des.department_id = $3)
        "#,
    )
    .bind(&search)
    .bind(&status)
    .bind(params.department_id)
    .fetch_one(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?
    .unwrap_or(0);

    Ok(Json(ListResponse {
        designations,
        total,
        page,
        per_page,
    }))
}

async fn get_designation(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let row = sqlx::query(
        r#"
        SELECT
            des.id,
            des.name,
            des.code,
            des.department_id,
            dep.name AS department_name,
            des.description,
            des.level,
            des.can_manage_team,
            des.can_approve,
            des.is_active,
            des.created_at,
            des.updated_at,
            COUNT(e.id) AS total_employees
        FROM designations des
        LEFT JOIN departments dep ON dep.id = des.department_id
        LEFT JOIN employees e ON e.designation_id = des.id
        WHERE des.id = $1
        GROUP BY des.id, dep.name
        "#,
    )
    .bind(id)
    .fetch_optional(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?
    .ok_or((StatusCode::NOT_FOUND, "Designation not found".to_string()))?;

    Ok(Json(DesignationRow {
        id: row.get("id"),
        name: row.get("name"),
        code: row.get("code"),
        department_id: row.get("department_id"),
        department_name: row.get("department_name"),
        description: row.get("description"),
        level: row.get("level"),
        can_manage_team: row.get("can_manage_team"),
        can_approve: row.get("can_approve"),
        is_active: row.get("is_active"),
        status: if row.get::<bool, _>("is_active") {
            "ACTIVE".to_string()
        } else {
            "INACTIVE".to_string()
        },
        total_employees: row.get("total_employees"),
        created_at: row.get("created_at"),
        updated_at: row.get("updated_at"),
    }))
}

async fn create_designation(
    State(state): State<AppState>,
    Json(payload): Json<CreateDesignationPayload>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let name = payload.name.trim();
    if name.is_empty() {
        return Err((StatusCode::BAD_REQUEST, "Name is required".to_string()));
    }

    let is_active = derive_is_active(&payload.status, payload.is_active, true);

    let row = sqlx::query(
        r#"
        INSERT INTO designations (
            name, code, department_id, description, level, can_manage_team, can_approve, is_active
        )
        VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
        RETURNING id
        "#,
    )
    .bind(name)
    .bind(payload.code.map(|v| v.trim().to_string()).filter(|v| !v.is_empty()))
    .bind(payload.department_id)
    .bind(payload.description.map(|v| v.trim().to_string()).filter(|v| !v.is_empty()))
    .bind(payload.level.map(|v| v.trim().to_string()).filter(|v| !v.is_empty()))
    .bind(payload.can_manage_team.unwrap_or(false))
    .bind(payload.can_approve.unwrap_or(false))
    .bind(is_active)
    .fetch_one(&state.pool)
    .await
    .map_err(|e| {
        let msg = e.to_string();
        if msg.contains("designations_name_key") || msg.contains("idx_designations_code_unique") {
            (StatusCode::CONFLICT, "Designation name or code already exists".to_string())
        } else {
            (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}"))
        }
    })?;

    let id: Uuid = row.get("id");
    let response = get_designation(State(state), Path(id)).await?;
    Ok((StatusCode::CREATED, response))
}

async fn update_designation(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
    Json(payload): Json<UpdateDesignationPayload>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let current = sqlx::query(
        r#"
        SELECT name, code, department_id, description, level, can_manage_team, can_approve, is_active
        FROM designations
        WHERE id = $1
        "#,
    )
    .bind(id)
    .fetch_optional(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?
    .ok_or((StatusCode::NOT_FOUND, "Designation not found".to_string()))?;

    let name = payload
        .name
        .map(|v| v.trim().to_string())
        .filter(|v| !v.is_empty())
        .unwrap_or_else(|| current.get::<String, _>("name"));
    let code = payload
        .code
        .map(|v| v.trim().to_string())
        .filter(|v| !v.is_empty())
        .or_else(|| current.get::<Option<String>, _>("code"));
    let department_id = payload
        .department_id
        .or_else(|| current.get::<Option<Uuid>, _>("department_id"));
    let description = payload
        .description
        .map(|v| v.trim().to_string())
        .filter(|v| !v.is_empty())
        .or_else(|| current.get::<Option<String>, _>("description"));
    let level = payload
        .level
        .map(|v| v.trim().to_string())
        .filter(|v| !v.is_empty())
        .or_else(|| current.get::<Option<String>, _>("level"));
    let is_active = derive_is_active(&payload.status, payload.is_active, current.get("is_active"));
    let can_manage_team = payload
        .can_manage_team
        .unwrap_or_else(|| current.get("can_manage_team"));
    let can_approve = payload
        .can_approve
        .unwrap_or_else(|| current.get("can_approve"));

    sqlx::query(
        r#"
        UPDATE designations
        SET
            name = $1,
            code = $2,
            department_id = $3,
            description = $4,
            level = $5,
            can_manage_team = $6,
            can_approve = $7,
            is_active = $8,
            updated_at = NOW()
        WHERE id = $9
        "#,
    )
    .bind(name)
    .bind(code)
    .bind(department_id)
    .bind(description)
    .bind(level)
    .bind(can_manage_team)
    .bind(can_approve)
    .bind(is_active)
    .bind(id)
    .execute(&state.pool)
    .await
    .map_err(|e| {
        let msg = e.to_string();
        if msg.contains("designations_name_key") || msg.contains("idx_designations_code_unique") {
            (StatusCode::CONFLICT, "Designation name or code already exists".to_string())
        } else {
            (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}"))
        }
    })?;

    get_designation(State(state), Path(id)).await
}

async fn delete_designation(
    State(state): State<AppState>,
    Path(id): Path<Uuid>,
) -> Result<impl IntoResponse, (StatusCode, String)> {
    let result = sqlx::query("DELETE FROM designations WHERE id = $1")
        .bind(id)
        .execute(&state.pool)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, format!("DB error: {e}")))?;

    if result.rows_affected() == 0 {
        return Err((StatusCode::NOT_FOUND, "Designation not found".to_string()));
    }

    Ok(StatusCode::NO_CONTENT)
}