using System.Collections.Generic;
using System.Data.Common;
using System.Threading.Tasks;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.DTO.WorkFlow;

namespace GB5Shared.WorkFlow.WorkFlowRunTime
{
    /// <summary>
    /// Low-level persistence contract for the workflow engine.
    /// All methods accept a <see cref="DbTransaction"/> so the engine can
    /// co-ordinate everything inside one database transaction.
    /// </summary>
    public interface IWorkFlowRunTime
    {
        // ── Config resolution ─────────────────────────────────────────────────

        /// <summary>
        /// Returns all MWORKFLOWCONFIG rows that might apply for the given context,
        /// ordered most-specific-first.  The engine evaluates EVALCONDITION on
        /// each row and picks the first match.
        /// </summary>
        Task<List<WorkflowConfigDTO>> GetWorkflowConfigsAsync(
            int entityId,
            int clientId,
            int ouId,
            int bizTransactionClassId,
            int bizTransactionId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>
        /// Looks up MBIZTRANSACTIONTYPE.BIZTRANSACTIONTYPEID by BizTransactionClassId.
        /// Returns -1 when no matching row exists (FK-safe fallback).
        /// </summary>
        Task<int> GetBizTransactionTypeIdAsync(
            int bizTransactionClassId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        // ── Definition load ───────────────────────────────────────────────────

        /// <summary>Loads a workflow by its PK (already resolved via MWORKFLOWCONFIG).</summary>
        Task<WorkflowDefinition?> GetWorkflowByIdAsync(
            int workflowId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>
        /// Loads the latest active workflow definition by EntityId + TenantId
        /// (kept for backward compat with old path).
        /// </summary>
        Task<WorkflowDefinition?> GetActiveDefinitionAsync(
            int entityId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>
        /// Legacy helper used by the old CheckWorkFlowApplicability path.
        /// Returns only the header row (no steps/transitions).
        /// </summary>
        Task<GetWorkFlowDTO?> GetActiveWorkflowAsync(
            int entityId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task<List<ConditionDTO>> GetConditionAsync(
            int? conditionGroupId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task<IDictionary<int, WorkflowRuleGroup>> GetRuleGroupsAsync(
            IEnumerable<int> ruleGroupIds,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        // ── Instance CRUD ─────────────────────────────────────────────────────

        /// <summary>
        /// Deletes any pending TWORKFLOWTASK and TWORKFLOWINSTANCE rows for the
        /// given tenant + entity + object before a fresh instance is inserted.
        /// Only rows with WORKFLOWSTATUS = 0 (Pending) are removed.
        /// </summary>
        Task DeleteDuplicateInstanceAsync(
            int entityId,
            int objectId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>
        /// Cancels every REAL pending (WORKFLOWSTATUS=0) instance for the given tenant +
        /// entity + object — unlike <see cref="DeleteDuplicateInstanceAsync"/>, this also
        /// cancels instances that already have history (i.e. a genuine in-flight approval),
        /// used when the underlying record is deleted or resubmitted after an edit. Also
        /// cancels the pending TWORKFLOWTASK rows and, for WIP-backed instances, the linked
        /// TWORKFLOWWIP row. Returns the instances that were cancelled so the caller can
        /// write TWORKFLOWHISTORY entries against each.
        /// </summary>
        Task<IReadOnlyList<WorkflowInstance>> CancelPendingInstancesAsync(
            int entityId,
            int objectId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task<WorkflowInstance> InsertInstanceAsync(
            WorkflowInstance instance,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task UpdateInstanceAsync(
            WorkflowInstance instance,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task<WorkflowInstance?> GetInstanceAsync(
            long instanceId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task<WorkflowInstance?> GetInstanceAsync(
            long clientId,
            string entityName,
            long entityId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        // ── Task CRUD ─────────────────────────────────────────────────────────

        Task<WorkflowTask> InsertTaskAsync(
            WorkflowTask task,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task UpdateTaskAsync(
            WorkflowTask task,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task<WorkflowTask?> GetTaskAsync(
            int taskId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>
        /// Returns all pending tasks for a given instance + approval level.
        /// Used to decide whether the level is complete.
        /// </summary>
        Task<IReadOnlyList<WorkflowTask>> GetPendingTasksForLevelAsync(
            int instanceId,
            int approvalLevel,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>Kept for backward compat (step-based parallel check).</summary>
        Task<IReadOnlyList<WorkflowTask>> GetPendingTasksForStepAsync(
            int instanceId,
            long stepId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        Task<IReadOnlyList<WorkflowTask>> GetInboxTasksAsync(
            long userId,
            IEnumerable<string>? roles,
            IEnumerable<string>? pools,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        // ── History ───────────────────────────────────────────────────────────

        Task InsertHistoryAsync(
            WorkflowHistory history,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        // ── Delegation ────────────────────────────────────────────────────────

        Task<IReadOnlyList<UserDelegation>> GetUserDelegationsAsync(
            long principalUserId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        // ── WIP (Form-Based Approval) ─────────────────────────────────────────

        /// <summary>
        /// Inserts a new TWORKFLOWWIP row (STATUS=Pending, WorkflowInstanceId=-1).
        /// Returns the new WipId.
        /// </summary>
        Task<int> InsertWipAsync(
            int    entityId,
            int    tenantId,
            string dataJson,
            string? loginJson,
            string? apiEndpoint,
            int    createdById,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>Binds the workflow instance to the WIP row after the instance is created.</summary>
        Task UpdateWipInstanceIdAsync(
            int wipId,
            int workflowInstanceId,
            int modifiedById,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>Returns the WIP record linked to a workflow instance, or null if this is not a WIP instance.</summary>
        Task<WorkflowWipDTO?> GetWipByInstanceIdAsync(
            int instanceId,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        /// <summary>Updates the WIP STATUS and LASTACTION; sets OBJECTID when the real entity has been saved.</summary>
        Task UpdateWipStatusAsync(
            int  wipId,
            byte status,
            byte lastAction,
            int  objectId,
            int  modifiedById,
            LoginDTO loginDTO,
            DbTransaction dbTransaction);

        // ── Auto-approve ──────────────────────────────────────────────────────

        /// <summary>
        /// Returns all pending tasks whose DUEON has passed and whose step
        /// has ISAUTOAPPROVE = 0 (0=Yes). Used by the background auto-approve job.
        /// </summary>
        Task<IReadOnlyList<OverdueAutoApproveTaskDTO>> GetOverdueAutoApproveTasksAsync(
            LoginDTO loginDTO,
            DbTransaction dbTransaction);
    }
}