-- Query log table for capturing form-based searches
-- Used to seed few-shot examples for NL2SQL agent

IF OBJECT_ID('dbo.controls_query_log', 'U') IS NULL
BEGIN
    CREATE TABLE dbo.controls_query_log (
        id              INT IDENTITY(1,1) PRIMARY KEY,
        user_query      NVARCHAR(1000)   NOT NULL,   -- Natural-language description of the search
        sql_template    NVARCHAR(MAX)    NOT NULL,   -- Parameterized SQL (placeholders like :tag, :start, :end)
        sql_template_hash AS CONVERT(VARBINARY(32), HASHBYTES('SHA2_256', sql_template)) PERSISTED,  -- For indexing
        params          NVARCHAR(MAX)    NULL,       -- JSON blob of actual parameter values
        source_form     NVARCHAR(100)    NULL,       -- Which form generated this (e.g., 'opcsearch', 'trend')
        user_session    NVARCHAR(100)    NULL,       -- Optional: session or user identifier
        execution_ms    INT              NULL,       -- Optional: query execution time in milliseconds
        row_count       INT              NULL,       -- Optional: number of rows returned
        created_at      DATETIME2        NOT NULL DEFAULT SYSUTCDATETIME()
    );

    -- Index on hash for deduplication and fast lookup
    CREATE NONCLUSTERED INDEX IX_controls_query_log_template_hash
        ON dbo.controls_query_log (sql_template_hash)
        INCLUDE (user_query, created_at);

    -- Index for time-based analysis
    CREATE NONCLUSTERED INDEX IX_controls_query_log_created
        ON dbo.controls_query_log (created_at DESC)
        INCLUDE (user_query, source_form);
END;
GO

-- View for distinct templates with example user queries
CREATE OR ALTER VIEW dbo.vw_controls_query_templates AS
SELECT
    sql_template,
    COUNT(*)                           AS usage_count,
    MAX(user_query)                    AS sample_user_query,
    MIN(created_at)                    AS first_used,
    MAX(created_at)                    AS last_used
FROM dbo.controls_query_log
GROUP BY sql_template;
GO