//! Persistence for workflow definitions (v1.2 Workflows).
//!
//! The `workflows` table (0071) is owner-polymorphic like `scripts`; M1 authors
//! **app-owned** workflows only (the `group_id` column ships unused). The read
//! trait backs the admin/CLI surface; the `*_tx` free-fns are used by the
//! declarative `apply` reconcile engine (Create/Update/Delete by `lower(name)`,
//! all in one transaction) — mirroring `trigger_repo::insert_trigger_tx`.
//!
//! Run/step state (`workflow_runs`, `workflow_run_steps`) is added in M2 with
//! the orchestrator.

use async_trait::async_trait;
use chrono::{DateTime, Utc};
use sqlx::PgPool;
use thiserror::Error;
use uuid::Uuid;

use picloud_shared::workflow::WorkflowDefinition;
use picloud_shared::{AppId, WorkflowId};

#[derive(Debug, Error)]
pub enum WorkflowRepoError {
    #[error(transparent)]
    Db(#[from] sqlx::Error),
    #[error("workflow definition (de)serialization failed: {0}")]
    Serde(String),
}

/// A stored workflow definition (app-owned in M1).
#[derive(Debug, Clone)]
pub struct Workflow {
    pub id: WorkflowId,
    pub app_id: AppId,
    pub name: String,
    pub definition: WorkflowDefinition,
    pub enabled: bool,
    pub created_at: DateTime<Utc>,
    pub updated_at: DateTime<Utc>,
}

/// Raw row shape (definition decoded separately).
#[derive(sqlx::FromRow)]
struct WorkflowRow {
    id: Uuid,
    app_id: Uuid,
    name: String,
    definition: serde_json::Value,
    enabled: bool,
    created_at: DateTime<Utc>,
    updated_at: DateTime<Utc>,
}

impl TryFrom<WorkflowRow> for Workflow {
    type Error = WorkflowRepoError;
    fn try_from(r: WorkflowRow) -> Result<Self, Self::Error> {
        Ok(Self {
            id: r.id.into(),
            app_id: r.app_id.into(),
            name: r.name,
            definition: serde_json::from_value(r.definition)
                .map_err(|e| WorkflowRepoError::Serde(e.to_string()))?,
            enabled: r.enabled,
            created_at: r.created_at,
            updated_at: r.updated_at,
        })
    }
}

const SELECT_COLS: &str = "id, app_id, name, definition, enabled, created_at, updated_at";

#[async_trait]
pub trait WorkflowRepo: Send + Sync {
    /// All workflows owned by `app_id`, ordered by name.
    async fn list_for_app(&self, app_id: AppId) -> Result<Vec<Workflow>, WorkflowRepoError>;
    /// A single app-owned workflow by case-insensitive name.
    async fn get_by_name(
        &self,
        app_id: AppId,
        name: &str,
    ) -> Result<Option<Workflow>, WorkflowRepoError>;
    /// A single workflow by id (app-scoped for isolation).
    async fn get_by_id(
        &self,
        app_id: AppId,
        id: WorkflowId,
    ) -> Result<Option<Workflow>, WorkflowRepoError>;
}

pub struct PostgresWorkflowRepo {
    pool: PgPool,
}

impl PostgresWorkflowRepo {
    #[must_use]
    pub fn new(pool: PgPool) -> Self {
        Self { pool }
    }
}

#[async_trait]
impl WorkflowRepo for PostgresWorkflowRepo {
    async fn list_for_app(&self, app_id: AppId) -> Result<Vec<Workflow>, WorkflowRepoError> {
        let rows: Vec<WorkflowRow> = sqlx::query_as(&format!(
            "SELECT {SELECT_COLS} FROM workflows WHERE app_id = $1 ORDER BY LOWER(name)"
        ))
        .bind(app_id.into_inner())
        .fetch_all(&self.pool)
        .await?;
        rows.into_iter().map(TryInto::try_into).collect()
    }

    async fn get_by_name(
        &self,
        app_id: AppId,
        name: &str,
    ) -> Result<Option<Workflow>, WorkflowRepoError> {
        let row: Option<WorkflowRow> = sqlx::query_as(&format!(
            "SELECT {SELECT_COLS} FROM workflows WHERE app_id = $1 AND LOWER(name) = LOWER($2)"
        ))
        .bind(app_id.into_inner())
        .bind(name)
        .fetch_optional(&self.pool)
        .await?;
        row.map(TryInto::try_into).transpose()
    }

    async fn get_by_id(
        &self,
        app_id: AppId,
        id: WorkflowId,
    ) -> Result<Option<Workflow>, WorkflowRepoError> {
        let row: Option<WorkflowRow> = sqlx::query_as(&format!(
            "SELECT {SELECT_COLS} FROM workflows WHERE app_id = $1 AND id = $2"
        ))
        .bind(app_id.into_inner())
        .bind(id.into_inner())
        .fetch_optional(&self.pool)
        .await?;
        row.map(TryInto::try_into).transpose()
    }
}

/// Pool-based read of an app's workflows (used by `apply`'s `load_current`,
/// which reads several markers directly off the pool).
pub async fn list_workflows_for_app(
    pool: &PgPool,
    app_id: AppId,
) -> Result<Vec<Workflow>, WorkflowRepoError> {
    let rows: Vec<WorkflowRow> = sqlx::query_as(&format!(
        "SELECT {SELECT_COLS} FROM workflows WHERE app_id = $1 ORDER BY LOWER(name)"
    ))
    .bind(app_id.into_inner())
    .fetch_all(pool)
    .await?;
    rows.into_iter().map(TryInto::try_into).collect()
}

// ---- reconcile tx free-fns (used by apply_service) ------------------------

/// Load an app's workflows inside the apply transaction (so the diff sees a
/// snapshot consistent with the writes).
pub async fn list_workflows_for_app_tx(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    app_id: AppId,
) -> Result<Vec<Workflow>, WorkflowRepoError> {
    let rows: Vec<WorkflowRow> = sqlx::query_as(&format!(
        "SELECT {SELECT_COLS} FROM workflows WHERE app_id = $1 ORDER BY LOWER(name)"
    ))
    .bind(app_id.into_inner())
    .fetch_all(&mut **tx)
    .await?;
    rows.into_iter().map(TryInto::try_into).collect()
}

/// Insert an app-owned workflow.
pub async fn insert_workflow_tx(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    app_id: AppId,
    name: &str,
    definition: &WorkflowDefinition,
    enabled: bool,
) -> Result<WorkflowId, WorkflowRepoError> {
    let def =
        serde_json::to_value(definition).map_err(|e| WorkflowRepoError::Serde(e.to_string()))?;
    let (id,): (Uuid,) = sqlx::query_as(
        "INSERT INTO workflows (app_id, name, definition, enabled) \
         VALUES ($1, $2, $3, $4) RETURNING id",
    )
    .bind(app_id.into_inner())
    .bind(name)
    .bind(def)
    .bind(enabled)
    .fetch_one(&mut **tx)
    .await?;
    Ok(id.into())
}

/// Update a workflow's definition + enabled flag (name/identity unchanged).
pub async fn update_workflow_tx(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    id: WorkflowId,
    definition: &WorkflowDefinition,
    enabled: bool,
) -> Result<(), WorkflowRepoError> {
    let def =
        serde_json::to_value(definition).map_err(|e| WorkflowRepoError::Serde(e.to_string()))?;
    sqlx::query(
        "UPDATE workflows SET definition = $2, enabled = $3, updated_at = NOW() WHERE id = $1",
    )
    .bind(id.into_inner())
    .bind(def)
    .bind(enabled)
    .execute(&mut **tx)
    .await?;
    Ok(())
}

/// Delete a workflow (prune). RESTRICTs if runs reference it — a workflow with
/// history is kept; this is surfaced as an error to the reconcile caller.
pub async fn delete_workflow_tx(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    id: WorkflowId,
) -> Result<(), WorkflowRepoError> {
    sqlx::query("DELETE FROM workflows WHERE id = $1")
        .bind(id.into_inner())
        .execute(&mut **tx)
        .await?;
    Ok(())
}