--
-- Stacks queries
-- All SQL for api/routes/stacks.js
--

SET search_path TO dataflow, public;

------------------------------------------------------
-- Tables
------------------------------------------------------

CREATE TABLE IF NOT EXISTS dataflow.stacks (
    name            TEXT PRIMARY KEY,
    label           TEXT,
    -- Ordered canonical field definitions: [{name, label, type}]
    -- type: 'text' | 'numeric' | 'date'
    fields          JSONB NOT NULL DEFAULT '[]',
    -- Running balance config
    amount_field    TEXT,           -- canonical field to sum for running balance
    date_field      TEXT,           -- canonical field to order by
    balance_offset  NUMERIC DEFAULT 0,  -- added to running sum (calibration)
    created_at      TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE IF NOT EXISTS dataflow.stack_sources (
    id              SERIAL PRIMARY KEY,
    stack_name      TEXT NOT NULL REFERENCES dataflow.stacks(name) ON DELETE CASCADE,
    source_name     TEXT NOT NULL REFERENCES dataflow.sources(name) ON DELETE CASCADE,
    -- Maps canonical field name → field name in records.transformed
    field_map       JSONB NOT NULL DEFAULT '{}',
    -- Multiply amount by this before summing (1 = as-is, -1 = flip sign)
    amount_sign     INTEGER NOT NULL DEFAULT 1,
    -- Seed balance for this source — added as a constant to the combined running total
    balance_offset  NUMERIC NOT NULL DEFAULT 0,
    UNIQUE (stack_name, source_name)
);

------------------------------------------------------
-- Function: list_stacks
------------------------------------------------------
CREATE OR REPLACE FUNCTION list_stacks()
RETURNS TABLE (
    name            TEXT,
    label           TEXT,
    fields          JSONB,
    amount_field    TEXT,
    date_field      TEXT,
    balance_offset  NUMERIC,
    source_count    BIGINT,
    created_at      TIMESTAMPTZ
) AS $$
    SELECT
        s.name, s.label, s.fields,
        s.amount_field, s.date_field, s.balance_offset,
        count(ss.id) AS source_count,
        s.created_at
    FROM dataflow.stacks s
    LEFT JOIN dataflow.stack_sources ss ON ss.stack_name = s.name
    GROUP BY s.name, s.label, s.fields, s.amount_field, s.date_field, s.balance_offset, s.created_at
    ORDER BY s.name;
$$ LANGUAGE sql STABLE;

------------------------------------------------------
-- Function: get_stack
------------------------------------------------------
CREATE OR REPLACE FUNCTION get_stack(p_name TEXT)
RETURNS TABLE (
    name            TEXT,
    label           TEXT,
    fields          JSONB,
    amount_field    TEXT,
    date_field      TEXT,
    balance_offset  NUMERIC,
    created_at      TIMESTAMPTZ,
    sources         JSONB
) AS $$
    SELECT
        s.name, s.label, s.fields,
        s.amount_field, s.date_field, s.balance_offset,
        s.created_at,
        COALESCE(jsonb_agg(
            jsonb_build_object(
                'id',             ss.id,
                'source_name',    ss.source_name,
                'field_map',      ss.field_map,
                'amount_sign',    ss.amount_sign,
                'balance_offset', ss.balance_offset
            ) ORDER BY ss.source_name
        ) FILTER (WHERE ss.id IS NOT NULL), '[]')
    FROM dataflow.stacks s
    LEFT JOIN dataflow.stack_sources ss ON ss.stack_name = s.name
    WHERE s.name = p_name
    GROUP BY s.name, s.label, s.fields, s.amount_field, s.date_field, s.balance_offset, s.created_at;
$$ LANGUAGE sql STABLE;

------------------------------------------------------
-- Function: create_stack
------------------------------------------------------
CREATE OR REPLACE FUNCTION create_stack(
    p_name          TEXT,
    p_label         TEXT DEFAULT NULL,
    p_fields        JSONB DEFAULT '[]',
    p_amount_field  TEXT DEFAULT NULL,
    p_date_field    TEXT DEFAULT NULL,
    p_balance_offset NUMERIC DEFAULT 0
) RETURNS dataflow.stacks AS $$
    INSERT INTO dataflow.stacks (name, label, fields, amount_field, date_field, balance_offset)
    VALUES (p_name, p_label, p_fields, p_amount_field, p_date_field, p_balance_offset)
    RETURNING *;
$$ LANGUAGE sql;

------------------------------------------------------
-- Function: update_stack
------------------------------------------------------
CREATE OR REPLACE FUNCTION update_stack(
    p_name           TEXT,
    p_label          TEXT DEFAULT NULL,
    p_fields         JSONB DEFAULT NULL,
    p_amount_field   TEXT DEFAULT NULL,
    p_date_field     TEXT DEFAULT NULL,
    p_balance_offset NUMERIC DEFAULT NULL
) RETURNS dataflow.stacks AS $$
    UPDATE dataflow.stacks SET
        label          = COALESCE(p_label, label),
        fields         = COALESCE(p_fields, fields),
        amount_field   = COALESCE(p_amount_field, amount_field),
        date_field     = COALESCE(p_date_field, date_field),
        balance_offset = COALESCE(p_balance_offset, balance_offset)
    WHERE name = p_name
    RETURNING *;
$$ LANGUAGE sql;

------------------------------------------------------
-- Function: delete_stack
------------------------------------------------------
CREATE OR REPLACE FUNCTION delete_stack(p_name TEXT)
RETURNS TABLE (name TEXT) AS $$
    DELETE FROM dataflow.stacks WHERE name = p_name RETURNING name;
$$ LANGUAGE sql;

------------------------------------------------------
-- Function: upsert_stack_source
------------------------------------------------------
CREATE OR REPLACE FUNCTION upsert_stack_source(
    p_stack_name      TEXT,
    p_source_name     TEXT,
    p_field_map       JSONB DEFAULT '{}',
    p_amount_sign     INTEGER DEFAULT 1,
    p_balance_offset  NUMERIC DEFAULT 0
) RETURNS dataflow.stack_sources AS $$
    INSERT INTO dataflow.stack_sources (stack_name, source_name, field_map, amount_sign, balance_offset)
    VALUES (p_stack_name, p_source_name, p_field_map, p_amount_sign, p_balance_offset)
    ON CONFLICT (stack_name, source_name) DO UPDATE SET
        field_map       = EXCLUDED.field_map,
        amount_sign     = EXCLUDED.amount_sign,
        balance_offset  = EXCLUDED.balance_offset
    RETURNING *;
$$ LANGUAGE sql;

------------------------------------------------------
-- Function: remove_stack_source
------------------------------------------------------
CREATE OR REPLACE FUNCTION remove_stack_source(p_stack_name TEXT, p_source_name TEXT)
RETURNS TABLE (source_name TEXT) AS $$
    DELETE FROM dataflow.stack_sources
    WHERE stack_name = p_stack_name AND source_name = p_source_name
    RETURNING source_name;
$$ LANGUAGE sql;

------------------------------------------------------
-- Function: calibrate_balance
-- Given a known good balance at a specific date, compute the offset needed.
-- Returns: {computed_at_date, known_balance, suggested_offset}
------------------------------------------------------
CREATE OR REPLACE FUNCTION calibrate_balance(
    p_stack_name    TEXT,
    p_source_name   TEXT,      -- specific source to calibrate, or NULL for combined
    p_as_of_date    DATE,
    p_known_balance NUMERIC
) RETURNS JSON AS $$
DECLARE
    v_stack     dataflow.stacks%ROWTYPE;
    v_running   NUMERIC := 0;
    v_other_offsets NUMERIC := 0;
BEGIN
    SELECT * INTO v_stack FROM dataflow.stacks WHERE name = p_stack_name;
    IF NOT FOUND THEN
        RETURN json_build_object('success', false, 'error', 'Stack not found');
    END IF;
    IF v_stack.amount_field IS NULL OR v_stack.date_field IS NULL THEN
        RETURN json_build_object('success', false, 'error', 'Stack must have amount_field and date_field set');
    END IF;

    -- Sum amount * sign for the target source(s) up to as_of_date
    SELECT COALESCE(SUM(
        (rec.transformed ->> (ss.field_map ->> v_stack.amount_field))::numeric
        * ss.amount_sign
    ), 0)
    INTO v_running
    FROM dataflow.stack_sources ss
    JOIN dataflow.records rec ON rec.source_name = ss.source_name
    WHERE ss.stack_name = p_stack_name
      AND (p_source_name IS NULL OR ss.source_name = p_source_name)
      AND rec.transformed IS NOT NULL
      AND (rec.transformed ->> (ss.field_map ->> v_stack.date_field))::date <= p_as_of_date;

    -- For combined calibration, include existing offsets from other sources
    IF p_source_name IS NOT NULL THEN
        SELECT COALESCE(SUM(balance_offset), 0) INTO v_other_offsets
        FROM dataflow.stack_sources
        WHERE stack_name = p_stack_name AND source_name != p_source_name;
    END IF;

    RETURN json_build_object(
        'success',          true,
        'source',           p_source_name,
        'as_of_date',       p_as_of_date,
        'known_balance',    p_known_balance,
        'computed_sum',     v_running,
        'other_offsets',    v_other_offsets,
        'suggested_offset', p_known_balance - v_running
    );
END;
$$ LANGUAGE plpgsql STABLE;

------------------------------------------------------
-- Function: generate_stack_view
-- Builds a UNION ALL view in dfv schema from all member sources.
-- Includes running_balance if amount_field and date_field are set.
------------------------------------------------------
CREATE OR REPLACE FUNCTION generate_stack_view(p_stack_name TEXT)
RETURNS JSON AS $$
DECLARE
    v_stack     dataflow.stacks%ROWTYPE;
    v_src       dataflow.stack_sources%ROWTYPE;
    v_field     JSONB;
    v_parts     TEXT[] := '{}';
    v_select    TEXT;
    v_col       TEXT;
    v_src_field TEXT;
    v_view      TEXT;
    v_sql       TEXT;
    v_has_bal   BOOLEAN;
BEGIN
    SELECT * INTO v_stack FROM dataflow.stacks WHERE name = p_stack_name;
    IF NOT FOUND THEN
        RETURN json_build_object('success', false, 'error', 'Stack not found');
    END IF;

    v_has_bal := v_stack.amount_field IS NOT NULL AND v_stack.date_field IS NOT NULL;

    -- Build one SELECT per source
    FOR v_src IN
        SELECT * FROM dataflow.stack_sources WHERE stack_name = p_stack_name ORDER BY source_name
    LOOP
        v_select := format('SELECT %L AS _source, rec.id AS _id', v_src.source_name);

        -- Canonical fields, mapped to source field names
        FOR v_field IN SELECT * FROM jsonb_array_elements(v_stack.fields)
        LOOP
            v_col      := v_field->>'name';
            v_src_field := COALESCE(v_src.field_map->>v_col, v_col);

            v_select := v_select || ', ' || CASE v_field->>'type'
                WHEN 'numeric' THEN
                    format('(rec.transformed->>%L)::numeric AS %I', v_src_field, v_col)
                WHEN 'date' THEN
                    format('(rec.transformed->>%L)::date AS %I', v_src_field, v_col)
                ELSE
                    format('rec.transformed->>%L AS %I', v_src_field, v_col)
            END;
        END LOOP;

        -- amount_sign column for running balance
        v_select := v_select || format(', %s::integer AS _sign, %s::numeric AS _src_offset', v_src.amount_sign, v_src.balance_offset);

        v_select := v_select || format(
            ' FROM dataflow.records rec WHERE rec.source_name = %L AND rec.transformed IS NOT NULL',
            v_src.source_name
        );

        v_parts := v_parts || v_select;
    END LOOP;

    IF array_length(v_parts, 1) IS NULL THEN
        RETURN json_build_object('success', false, 'error', 'Stack has no sources');
    END IF;

    CREATE SCHEMA IF NOT EXISTS dfv;
    v_view := 'dfv.' || quote_ident(p_stack_name);
    EXECUTE format('DROP VIEW IF EXISTS %s', v_view);

    -- Wrap in outer SELECT that adds running_balance if configured
    IF v_has_bal THEN
        -- running_balance = cumulative sum of (amount * sign) + per-source seed offsets + stack-level offset
        -- Each row's _src_offset is that source's balance_offset, summed cumulatively so it's added once
        -- per source in the window rather than per row. We use a trick: sum(_src_offset / count_of_source_rows)
        -- is complex, so instead we add SUM(DISTINCT _src_offset per _source) as a constant via subquery.
        -- Simpler: treat each source offset as a lump added to its first row only via ROW_NUMBER trick.
        -- Cleanest: add total of all source offsets as a constant (valid when each source is calibrated
        -- relative to its own transaction history, not to each other).
        v_sql := format(
            'CREATE VIEW %s AS '
            'SELECT _source, _id, %s, '
            'SUM((%I)::numeric * _sign) OVER (ORDER BY %I ASC, _id ASC) '
            '+ (SELECT COALESCE(SUM(balance_offset),0) FROM dataflow.stack_sources WHERE stack_name = %L) '
            '+ %s AS running_balance '
            'FROM (%s) _stacked',
            v_view,
            (SELECT string_agg(quote_ident(f->>'name'), ', ')
             FROM jsonb_array_elements(v_stack.fields) f),
            v_stack.amount_field,
            v_stack.date_field,
            p_stack_name,
            v_stack.balance_offset,
            array_to_string(v_parts, ' UNION ALL ')
        );
    ELSE
        v_sql := format(
            'CREATE VIEW %s AS SELECT _source, _id, %s FROM (%s) _stacked',
            v_view,
            (SELECT string_agg(quote_ident(f->>'name'), ', ')
             FROM jsonb_array_elements(v_stack.fields) f),
            array_to_string(v_parts, ' UNION ALL ')
        );
    END IF;

    EXECUTE v_sql;

    RETURN json_build_object('success', true, 'view', v_view, 'sql', v_sql);
END;
$$ LANGUAGE plpgsql;

COMMENT ON FUNCTION generate_stack_view IS 'Generate a UNION ALL view in dfv schema combining multiple sources with optional running balance';
COMMENT ON FUNCTION calibrate_balance IS 'Given a known good balance at a date, compute the offset to add to balance_offset';