// src/table_definition/handlers/post_table_definition.rs
use tonic::Status;
use sqlx::PgPool;
use serde_json::json;
use time::OffsetDateTime;
use common::proto::multieko2::table_definition::{PostTableDefinitionRequest, TableDefinitionResponse};

const VALID_DATA_TYPES: &[&str] = &["TEXT", "INTEGER", "BIGINT", "BOOLEAN", "TIMESTAMPTZ", "NUMERIC"];

fn is_valid_data_type(dt: &str) -> bool {
    VALID_DATA_TYPES.contains(&dt.to_uppercase().as_str())
}

fn is_valid_identifier(s: &str) -> bool {
    let parts: Vec<&str> = s.split('_').collect();
    
    parts.len() >= 3 &&
    parts[0] == "ud" &&
    parts[1].len() == 4 && 
    parts[1].chars().all(|c| c.is_ascii_digit()) &&
    parts[2..].iter().all(|p| !p.is_empty()) &&
    s.chars().all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '_')
}

fn sanitize_identifier(s: &str) -> String {
    let year = OffsetDateTime::now_utc().year();
    let cleaned = s.replace(|c: char| !c.is_ascii_alphanumeric() && c != '_', "")
        .trim()
        .to_lowercase();
        
    format!("ud_{}_{}", year, cleaned)
}

pub async fn post_table_definition(
    db_pool: &PgPool,
    mut request: PostTableDefinitionRequest,
) -> Result<TableDefinitionResponse, Status> {
    // Validate and sanitize inputs
    let table_name = sanitize_identifier(&request.table_name);
    if !is_valid_identifier(&table_name) {
        return Err(Status::invalid_argument("Invalid table name"));
    }

    // Lookup or create profile
    let profile = sqlx::query!(
        "INSERT INTO profiles (name) VALUES ($1)
         ON CONFLICT (name) DO UPDATE SET name = EXCLUDED.name
         RETURNING id",
        request.profile_name
    )
    .fetch_one(db_pool)
    .await
    .map_err(|e| Status::internal(format!("Profile error: {}", e)))?;

    // Validate linked table if provided
    let linked_table_id;
    let linked_table_name = request.linked_table_name
        .as_ref()
        .map(|lt| sanitize_identifier(lt));

    if let Some(lt_name) = &linked_table_name {
        let lt_record = sqlx::query!(
            "SELECT id FROM table_definitions
            WHERE profile_id = $1 AND table_name = $2",
            profile.id,
            lt_name
        )
        .fetch_optional(db_pool)
        .await
        .map_err(|e| Status::internal(format!("Linked table lookup failed: {}", e)))?;

        linked_table_id = match lt_record {
            Some(r) => Some(r.id),
            None => return Err(Status::not_found("Linked table not found in profile")),
        };
    } else {
        linked_table_id = None;
    }

    // Validate columns and indexes
    let mut columns = Vec::new();
    for col_def in request.columns.drain(..) {
        let col_name = sanitize_identifier(&col_def.name);
        if !is_valid_identifier(&col_name) {
            return Err(Status::invalid_argument("Invalid column name"));
        }
        if !is_valid_data_type(&col_def.data_type) {
            return Err(Status::invalid_argument("Invalid data type"));
        }
        columns.push(format!("\"{}\" {}", col_name, col_def.data_type));
    }

    let mut indexes = Vec::new();
    for idx in request.indexes.drain(..) {
        let idx_name = sanitize_identifier(&idx);
        if !is_valid_identifier(&idx_name) {
            return Err(Status::invalid_argument(format!("Invalid index name: {}", idx)));
        }
        indexes.push(idx_name);
    }

    // Generate SQL
    let (create_sql, index_sql) = generate_table_sql(
        &table_name,
        &columns,
        &indexes,
        linked_table_name.as_deref()
    );

    // Store definition
    sqlx::query!(
        r#"INSERT INTO table_definitions
        (profile_id, table_name, columns, indexes, linked_table_id)
        VALUES ($1, $2, $3, $4, $5)"#,
        profile.id,
        &table_name,
        json!(columns),
        json!(indexes),
        linked_table_id
    )
    .execute(db_pool)
    .await
    .map_err(|e| {
        if let Some(db_err) = e.as_database_error() {
            if db_err.constraint() == Some("idx_table_definitions_profile_table") {
                return Status::already_exists("Table already exists in this profile");
            }
        }
        Status::internal(format!("Database error: {}", e))
    })?;

    // Execute generated SQL
    sqlx::query(&create_sql)
        .execute(db_pool)
        .await
        .map_err(|e| Status::internal(format!("Table creation failed: {}", e)))?;

    for sql in &index_sql {
        sqlx::query(&sql)
            .execute(db_pool)
            .await
            .map_err(|e| Status::internal(format!("Index creation failed: {}", e)))?;
    }

    Ok(TableDefinitionResponse {
        success: true,
        sql: format!("{}\n{}", create_sql, index_sql.join("\n")),
    })
}

fn generate_table_sql(
    table_name: &str,
    columns: &[String],
    indexes: &[String],
    linked_table: Option<&str>,
) -> (String, Vec<String>) {
    let mut system_columns = vec![
        "id BIGSERIAL PRIMARY KEY".to_string(),
        "deleted BOOLEAN NOT NULL DEFAULT FALSE".to_string(),
        "firma TEXT NOT NULL".to_string(),
    ];

    if let Some(linked) = linked_table {
        // Extract base name without prefix for relationship
        let parts: Vec<&str> = linked.splitn(3, '_').collect();
        let base_name = parts.get(2).unwrap_or(&linked);
        
        system_columns.push(
            format!("\"{}_id\" BIGINT NOT NULL REFERENCES \"{}\"(id)", 
                base_name, 
                linked
            )
        );
    }

    let all_columns = system_columns
        .iter()
        .chain(columns.iter())
        .cloned()
        .collect::<Vec<_>>();

    let create_sql = format!(
        "CREATE TABLE \"{}\" (\n    {},\n    created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP\n)",
        table_name,
        all_columns.join(",\n    ")
    );

    let mut system_indexes = vec![
        format!("CREATE INDEX idx_{}_firma ON \"{}\" (firma)", table_name, table_name),
    ];

    if let Some(linked) = linked_table {
        system_indexes.push(format!(
            "CREATE INDEX idx_{}_{}_id ON \"{}\" (\"{}_id\")",
            table_name, linked, table_name, linked
        ));
    }

    let all_indexes = system_indexes
        .into_iter()
        .chain(indexes.iter().map(|idx| {
            format!("CREATE INDEX idx_{}_{} ON \"{}\" (\"{}\")",
                table_name, idx, table_name, idx)
        }))
        .collect::<Vec<_>>();

    (create_sql, all_indexes)
}