use std::collections::BTreeMap;

use async_trait::async_trait;
use picloud_orchestrator_core::{ResolverError, ScriptResolver};
use picloud_shared::{
    AdminUserId, AppId, ExecutionLog, ExecutionStatus, RequestId, Script, ScriptId, ScriptKind,
    ScriptSandbox,
};
use sqlx::PgPool;

#[derive(Debug, thiserror::Error)]
pub enum ScriptRepositoryError {
    #[error("database error: {0}")]
    Db(#[from] sqlx::Error),

    #[error("not found: {0}")]
    NotFound(ScriptId),

    #[error("conflict: {0}")]
    Conflict(String),
}

/// CRUD over the `scripts` table.
#[async_trait]
pub trait ScriptRepository: Send + Sync {
    async fn get(&self, id: ScriptId) -> Result<Option<Script>, ScriptRepositoryError>;
    /// Every script across all apps. Mostly for tests and admin
    /// "global" views; the dashboard reaches scripts via `list_for_app`.
    async fn list(&self) -> Result<Vec<Script>, ScriptRepositoryError>;
    async fn list_for_app(&self, app_id: AppId) -> Result<Vec<Script>, ScriptRepositoryError>;
    /// Every script in any app the user is a member of. Drives
    /// `GET /admin/scripts` for `member` instance-role callers so the
    /// API never returns scripts they shouldn't see — even before the
    /// per-handler capability check fires.
    async fn list_for_user(
        &self,
        user_id: AdminUserId,
    ) -> Result<Vec<Script>, ScriptRepositoryError>;
    async fn create(&self, input: NewScript) -> Result<Script, ScriptRepositoryError>;
    async fn update(
        &self,
        id: ScriptId,
        patch: ScriptPatch,
    ) -> Result<Script, ScriptRepositoryError>;
    async fn delete(&self, id: ScriptId) -> Result<(), ScriptRepositoryError>;

    /// v1.1.3: how many routes reference this script. Used by the
    /// API layer to refuse `endpoint → module` kind changes when the
    /// script is still bound to user-facing entry points.
    async fn count_routes_for_script(
        &self,
        script_id: ScriptId,
    ) -> Result<i64, ScriptRepositoryError>;

    /// v1.1.3: how many triggers (kv / docs / dead-letter) target
    /// this script. Same purpose as `count_routes_for_script`.
    async fn count_triggers_for_script(
        &self,
        script_id: ScriptId,
    ) -> Result<i64, ScriptRepositoryError>;

    /// v1.1.3: list module dependencies of this script — the rows in
    /// `script_imports` where `importer_script_id = script_id`. Used
    /// by tests and (eventually) a dashboard "Imports" panel.
    async fn list_imports(
        &self,
        script_id: ScriptId,
    ) -> Result<Vec<Script>, ScriptRepositoryError>;
}

/// Inbound shape for create. Defaults match the migration's CHECK
/// constraints; the repo enforces them in the DB regardless.
#[derive(Debug, Clone)]
pub struct NewScript {
    pub app_id: AppId,
    pub name: String,
    pub description: Option<String>,
    pub source: String,
    /// Defaults to `Endpoint` if absent. `Module` scripts cannot be
    /// bound to routes or used as trigger targets.
    pub kind: ScriptKind,
    pub timeout_seconds: Option<i32>,
    pub memory_limit_mb: Option<i32>,
    /// Sandbox overrides; `None` means store an empty object (use
    /// platform defaults at exec time).
    pub sandbox: Option<ScriptSandbox>,
    /// v1.1.3: literal-path `import "<name>"` declarations extracted
    /// from the source. The repo writes these into `script_imports`
    /// transactionally with the script row. Empty when validation
    /// found no imports (the common case for endpoints today).
    pub imports: Vec<String>,
}

/// Inbound shape for update. `None` fields are left untouched.
#[derive(Debug, Clone, Default)]
pub struct ScriptPatch {
    pub name: Option<String>,
    pub description: Option<Option<String>>,
    pub source: Option<String>,
    pub timeout_seconds: Option<i32>,
    pub memory_limit_mb: Option<i32>,
    /// `Some(sandbox)` replaces the stored overrides wholesale (including
    /// `Some(empty)` to clear them); `None` leaves them untouched.
    pub sandbox: Option<ScriptSandbox>,
    /// `Some(new_kind)` changes the script's role; the API layer
    /// rejects unsafe transitions (e.g. endpoint→module when routes
    /// or triggers reference the script).
    pub kind: Option<ScriptKind>,
    /// v1.1.3: when `source` is also `Some`, the repo replaces the
    /// `script_imports` edges for this script with these names.
    /// `None` keeps the existing edges untouched (a name/description
    /// edit alone shouldn't touch the dep graph).
    pub imports: Option<Vec<String>>,
}

pub struct PostgresScriptRepository {
    pool: PgPool,
}

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

    #[must_use]
    pub fn pool(&self) -> &PgPool {
        &self.pool
    }
}

/// Columns selected from `scripts` everywhere — kept in one constant so
/// adding `kind` (v1.1.3) and future columns can't accidentally skip
/// one query.
const SCRIPT_SELECT_COLS: &str = "id, app_id, name, description, version, source, kind, \
                                  timeout_seconds, memory_limit_mb, sandbox, created_at, updated_at";

#[async_trait]
impl ScriptRepository for PostgresScriptRepository {
    async fn get(&self, id: ScriptId) -> Result<Option<Script>, ScriptRepositoryError> {
        let row = sqlx::query_as::<_, ScriptRow>(&format!(
            "SELECT {SCRIPT_SELECT_COLS} FROM scripts WHERE id = $1"
        ))
        .bind(id.into_inner())
        .fetch_optional(&self.pool)
        .await?;
        Ok(row.map(Into::into))
    }

    async fn list(&self) -> Result<Vec<Script>, ScriptRepositoryError> {
        let rows = sqlx::query_as::<_, ScriptRow>(&format!(
            "SELECT {SCRIPT_SELECT_COLS} FROM scripts ORDER BY name"
        ))
        .fetch_all(&self.pool)
        .await?;
        Ok(rows.into_iter().map(Into::into).collect())
    }

    async fn list_for_app(&self, app_id: AppId) -> Result<Vec<Script>, ScriptRepositoryError> {
        let rows = sqlx::query_as::<_, ScriptRow>(&format!(
            "SELECT {SCRIPT_SELECT_COLS} FROM scripts WHERE app_id = $1 ORDER BY name"
        ))
        .bind(app_id.into_inner())
        .fetch_all(&self.pool)
        .await?;
        Ok(rows.into_iter().map(Into::into).collect())
    }

    async fn list_for_user(
        &self,
        user_id: AdminUserId,
    ) -> Result<Vec<Script>, ScriptRepositoryError> {
        let cols = SCRIPT_SELECT_COLS
            .split(", ")
            .map(|c| format!("s.{c}"))
            .collect::<Vec<_>>()
            .join(", ");
        let rows = sqlx::query_as::<_, ScriptRow>(&format!(
            "SELECT {cols} FROM scripts s \
             JOIN app_members m ON m.app_id = s.app_id \
             WHERE m.user_id = $1 \
             ORDER BY s.name"
        ))
        .bind(user_id.into_inner())
        .fetch_all(&self.pool)
        .await?;
        Ok(rows.into_iter().map(Into::into).collect())
    }

    async fn create(&self, input: NewScript) -> Result<Script, ScriptRepositoryError> {
        let sandbox_json = serde_json::to_value(input.sandbox.unwrap_or_default())
            .unwrap_or_else(|_| serde_json::json!({}));
        let mut tx = self.pool.begin().await?;
        let res = sqlx::query_as::<_, ScriptRow>(&format!(
            "INSERT INTO scripts ( \
                app_id, name, description, source, kind, \
                timeout_seconds, memory_limit_mb, sandbox \
             ) VALUES ($1, $2, $3, $4, $5, COALESCE($6, 30), COALESCE($7, 256), $8) \
             RETURNING {SCRIPT_SELECT_COLS}"
        ))
        .bind(input.app_id.into_inner())
        .bind(&input.name)
        .bind(input.description.as_deref())
        .bind(&input.source)
        .bind(input.kind.as_str())
        .bind(input.timeout_seconds)
        .bind(input.memory_limit_mb)
        .bind(sandbox_json)
        .fetch_one(&mut *tx)
        .await;

        let script: Script = match res {
            Ok(row) => row.into(),
            Err(sqlx::Error::Database(e)) if e.is_unique_violation() => {
                return Err(ScriptRepositoryError::Conflict(format!(
                    "a script named {:?} already exists in this app",
                    input.name
                )));
            }
            Err(e) => return Err(e.into()),
        };

        // Dep-graph: write any literal-path imports declared in the
        // source. Unresolved names (the referenced module doesn't
        // exist yet) are silently skipped — best-effort.
        replace_imports_tx(&mut tx, script.id, script.app_id, &input.imports).await?;
        tx.commit().await?;
        Ok(script)
    }

    async fn update(
        &self,
        id: ScriptId,
        patch: ScriptPatch,
    ) -> Result<Script, ScriptRepositoryError> {
        // COALESCE-based partial update: `NULL` parameters leave columns
        // untouched. Description is double-Optioned so callers can
        // explicitly set it to NULL (Some(None)) vs leave it alone (None).
        // Sandbox is replaced wholesale when present; per-field merging
        // happens in the API layer (clearer semantics for a "PUT a new
        // sandbox config" call). app_id is immutable — moving a script
        // to another app is a copy-and-delete, not an in-place edit.
        let sandbox_json = patch
            .sandbox
            .as_ref()
            .map(|s| serde_json::to_value(s).unwrap_or_else(|_| serde_json::json!({})));
        let mut tx = self.pool.begin().await?;
        let res = sqlx::query_as::<_, ScriptRow>(&format!(
            "UPDATE scripts SET \
                name = COALESCE($2, name), \
                description = CASE WHEN $3::bool THEN $4 ELSE description END, \
                source = COALESCE($5, source), \
                timeout_seconds = COALESCE($6, timeout_seconds), \
                memory_limit_mb = COALESCE($7, memory_limit_mb), \
                sandbox = COALESCE($8, sandbox), \
                kind = COALESCE($9, kind), \
                version = version + 1, \
                updated_at = NOW() \
             WHERE id = $1 \
             RETURNING {SCRIPT_SELECT_COLS}"
        ))
        .bind(id.into_inner())
        .bind(patch.name.as_deref())
        .bind(patch.description.is_some())
        .bind(patch.description.as_ref().and_then(|d| d.as_deref()))
        .bind(patch.source.as_deref())
        .bind(patch.timeout_seconds)
        .bind(patch.memory_limit_mb)
        .bind(sandbox_json)
        .bind(patch.kind.map(|k| k.as_str()))
        .fetch_optional(&mut *tx)
        .await;

        let script: Script = match res {
            Ok(Some(row)) => row.into(),
            Ok(None) => return Err(ScriptRepositoryError::NotFound(id)),
            Err(sqlx::Error::Database(e)) if e.is_unique_violation() => {
                return Err(ScriptRepositoryError::Conflict(
                    "a script with that name already exists in this app".into(),
                ));
            }
            Err(e) => return Err(e.into()),
        };

        // Replace imports only when the caller has a fresh list (i.e.
        // the source actually changed and the validator re-extracted
        // imports). A name-only or description-only edit leaves the
        // dep graph alone.
        if let Some(imports) = patch.imports.as_deref() {
            replace_imports_tx(&mut tx, script.id, script.app_id, imports).await?;
        }
        tx.commit().await?;
        Ok(script)
    }

    async fn delete(&self, id: ScriptId) -> Result<(), ScriptRepositoryError> {
        let res = sqlx::query("DELETE FROM scripts WHERE id = $1")
            .bind(id.into_inner())
            .execute(&self.pool)
            .await?;
        if res.rows_affected() == 0 {
            return Err(ScriptRepositoryError::NotFound(id));
        }
        Ok(())
    }

    async fn count_routes_for_script(
        &self,
        script_id: ScriptId,
    ) -> Result<i64, ScriptRepositoryError> {
        let n: (i64,) = sqlx::query_as("SELECT COUNT(*) FROM routes WHERE script_id = $1")
            .bind(script_id.into_inner())
            .fetch_one(&self.pool)
            .await?;
        Ok(n.0)
    }

    async fn count_triggers_for_script(
        &self,
        script_id: ScriptId,
    ) -> Result<i64, ScriptRepositoryError> {
        let n: (i64,) = sqlx::query_as("SELECT COUNT(*) FROM triggers WHERE script_id = $1")
            .bind(script_id.into_inner())
            .fetch_one(&self.pool)
            .await?;
        Ok(n.0)
    }

    async fn list_imports(
        &self,
        script_id: ScriptId,
    ) -> Result<Vec<Script>, ScriptRepositoryError> {
        let cols = SCRIPT_SELECT_COLS
            .split(", ")
            .map(|c| format!("s.{c}"))
            .collect::<Vec<_>>()
            .join(", ");
        let rows = sqlx::query_as::<_, ScriptRow>(&format!(
            "SELECT {cols} FROM scripts s \
             JOIN script_imports i ON i.imported_script_id = s.id \
             WHERE i.importer_script_id = $1 \
             ORDER BY s.name"
        ))
        .bind(script_id.into_inner())
        .fetch_all(&self.pool)
        .await?;
        Ok(rows.into_iter().map(Into::into).collect())
    }
}

/// Replace the `script_imports` edges for `importer` with rows derived
/// from `import_names`. Names that don't resolve to a `kind = 'module'`
/// script in the same app are silently skipped (best-effort dep graph).
async fn replace_imports_tx(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    importer: ScriptId,
    app_id: AppId,
    import_names: &[String],
) -> Result<(), ScriptRepositoryError> {
    sqlx::query("DELETE FROM script_imports WHERE importer_script_id = $1")
        .bind(importer.into_inner())
        .execute(&mut **tx)
        .await?;
    if import_names.is_empty() {
        return Ok(());
    }
    // Insert with ON CONFLICT DO NOTHING in case the source declares
    // `import "x"` twice — the dep graph stores each pair at most once.
    sqlx::query(
        "INSERT INTO script_imports (app_id, importer_script_id, imported_script_id) \
         SELECT $1, $2, s.id \
         FROM scripts s \
         WHERE s.app_id = $1 \
           AND s.kind = 'module' \
           AND s.id <> $2 \
           AND s.name = ANY($3) \
         ON CONFLICT DO NOTHING",
    )
    .bind(app_id.into_inner())
    .bind(importer.into_inner())
    .bind(import_names)
    .execute(&mut **tx)
    .await?;
    Ok(())
}

/// Row shape mirroring the `scripts` table for sqlx FromRow.
#[derive(sqlx::FromRow)]
struct ScriptRow {
    id: uuid::Uuid,
    app_id: uuid::Uuid,
    name: String,
    description: Option<String>,
    version: i32,
    source: String,
    /// v1.1.3: 'endpoint' | 'module'. Stored as TEXT with a CHECK
    /// constraint so we don't need a Postgres enum (avoiding the
    /// migration churn of adding values later).
    kind: String,
    timeout_seconds: i32,
    memory_limit_mb: i32,
    sandbox: serde_json::Value,
    created_at: chrono::DateTime<chrono::Utc>,
    updated_at: chrono::DateTime<chrono::Utc>,
}

impl From<ScriptRow> for Script {
    fn from(r: ScriptRow) -> Self {
        // Tolerate stale rows whose sandbox column predates a future
        // schema migration: unknown fields are rejected by serde, so
        // fall back to an empty ScriptSandbox rather than poisoning a
        // list response.
        let sandbox = serde_json::from_value(r.sandbox).unwrap_or_default();
        // Defensive: if a row's `kind` somehow falls outside the CHECK
        // constraint, treat it as Endpoint (the safe default — won't
        // grant a row import-target status it doesn't have).
        let kind = ScriptKind::from_str(&r.kind).unwrap_or(ScriptKind::Endpoint);
        Self {
            id: r.id.into(),
            app_id: r.app_id.into(),
            name: r.name,
            description: r.description,
            version: r.version,
            source: r.source,
            kind,
            timeout_seconds: u32::try_from(r.timeout_seconds).unwrap_or(30),
            memory_limit_mb: u32::try_from(r.memory_limit_mb).unwrap_or(256),
            sandbox,
            created_at: r.created_at,
            updated_at: r.updated_at,
        }
    }
}

/// Adapts a `ScriptRepository` into the `ScriptResolver` trait the
/// orchestrator depends on. Keeps orchestrator-core unaware of how
/// scripts are stored.
pub struct RepoResolver<R: ScriptRepository> {
    repo: R,
}

impl<R: ScriptRepository> RepoResolver<R> {
    pub fn new(repo: R) -> Self {
        Self { repo }
    }
}

#[async_trait]
impl<R: ScriptRepository> ScriptResolver for RepoResolver<R> {
    async fn resolve(&self, id: ScriptId) -> Result<Option<Script>, ResolverError> {
        self.repo
            .get(id)
            .await
            .map_err(|e| ResolverError::Backend(e.to_string()))
    }
}

// ----------------------------------------------------------------------------
// Execution log repository (read side)
// ----------------------------------------------------------------------------

/// Read-side access to the `execution_logs` table. Writes go through
/// `PostgresExecutionLogSink` so the read and write paths can diverge
/// in cluster mode without disturbing this trait.
#[async_trait]
pub trait ExecutionLogRepository: Send + Sync {
    async fn list_for_script(
        &self,
        script_id: ScriptId,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<ExecutionLog>, ScriptRepositoryError>;
}

pub struct PostgresExecutionLogRepository {
    pool: PgPool,
}

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

#[async_trait]
impl ExecutionLogRepository for PostgresExecutionLogRepository {
    async fn list_for_script(
        &self,
        script_id: ScriptId,
        limit: i64,
        offset: i64,
    ) -> Result<Vec<ExecutionLog>, ScriptRepositoryError> {
        let rows = sqlx::query_as::<_, ExecutionLogRow>(
            "SELECT id, app_id, script_id, request_id, \
                    request_path, request_headers, request_body, \
                    response_code, response_body, \
                    logs, duration_ms, status, created_at \
             FROM execution_logs \
             WHERE script_id = $1 \
             ORDER BY created_at DESC \
             LIMIT $2 OFFSET $3",
        )
        .bind(script_id.into_inner())
        .bind(limit)
        .bind(offset)
        .fetch_all(&self.pool)
        .await?;

        Ok(rows.into_iter().map(Into::into).collect())
    }
}

#[derive(sqlx::FromRow)]
struct ExecutionLogRow {
    id: uuid::Uuid,
    app_id: uuid::Uuid,
    script_id: uuid::Uuid,
    request_id: uuid::Uuid,
    request_path: Option<String>,
    request_headers: serde_json::Value,
    request_body: Option<serde_json::Value>,
    response_code: Option<i32>,
    response_body: Option<serde_json::Value>,
    logs: serde_json::Value,
    duration_ms: i32,
    status: String,
    created_at: chrono::DateTime<chrono::Utc>,
}

impl From<ExecutionLogRow> for ExecutionLog {
    fn from(r: ExecutionLogRow) -> Self {
        let headers: BTreeMap<String, String> =
            serde_json::from_value(r.request_headers).unwrap_or_default();
        let status = match r.status.as_str() {
            "success" => ExecutionStatus::Success,
            "timeout" => ExecutionStatus::Timeout,
            "budget_exceeded" => ExecutionStatus::BudgetExceeded,
            _ => ExecutionStatus::Error,
        };
        Self {
            id: r.id,
            app_id: r.app_id.into(),
            script_id: r.script_id.into(),
            request_id: RequestId::from(r.request_id),
            request_path: r.request_path.unwrap_or_default(),
            request_headers: headers,
            request_body: r.request_body.unwrap_or(serde_json::Value::Null),
            response_code: r.response_code.and_then(|c| u16::try_from(c).ok()),
            response_body: r.response_body,
            script_logs: r.logs,
            duration_ms: u64::try_from(r.duration_ms).unwrap_or(0),
            status,
            created_at: r.created_at,
        }
    }
}