--
-- 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 other canonical field names → source view column names (not amount/date — those are explicit)
    field_map       JSONB NOT NULL DEFAULT '{}',
    -- Which column in dfv.{source} is the amount, and its sign (+1/-1)
    amount_field    TEXT,
    amount_sign     INTEGER NOT NULL DEFAULT 1,
    -- Which column in dfv.{source} is the date
    date_field      TEXT,
    -- Calibration offset added to this source's running balance
    balance_offset  NUMERIC NOT NULL DEFAULT 0,
    UNIQUE (stack_name, source_name)
);

-- Migrations: add columns that may be missing from earlier deploys
ALTER TABLE dataflow.stack_sources ADD COLUMN IF NOT EXISTS balance_offset NUMERIC NOT NULL DEFAULT 0;
ALTER TABLE dataflow.stack_sources ADD COLUMN IF NOT EXISTS amount_field TEXT;
ALTER TABLE dataflow.stack_sources ADD COLUMN IF NOT EXISTS date_field TEXT;
ALTER TABLE dataflow.stack_sources ADD COLUMN IF NOT EXISTS seq INTEGER NOT NULL DEFAULT 0;

-- Seed seq from insertion order for existing rows
UPDATE dataflow.stack_sources ss
SET seq = sub.rn
FROM (
    SELECT id, ROW_NUMBER() OVER (PARTITION BY stack_name ORDER BY id) AS rn
    FROM dataflow.stack_sources WHERE seq = 0
) sub
WHERE ss.id = sub.id AND ss.seq = 0;

-- Drop old signatures before recreating
DROP FUNCTION IF EXISTS calibrate_balance(TEXT, DATE, NUMERIC);
DROP FUNCTION IF EXISTS upsert_stack_source(TEXT, TEXT, JSONB, INTEGER, NUMERIC);
DROP FUNCTION IF EXISTS generate_stack_view(TEXT);

------------------------------------------------------
-- 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 $$
    SELECT
        s.name, s.label, s.fields,
        s.amount_field, s.date_field, s.balance_offset,
        s.created_at,
        COALESCE(jsonb_agg(
            jsonb_build_object(
                'id',             ss.id,
                'source_name',    ss.source_name,
                'field_map',      ss.field_map,
                'amount_field',   ss.amount_field,
                'amount_sign',    ss.amount_sign,
                'date_field',     ss.date_field,
                'balance_offset', ss.balance_offset,
                'seq',            ss.seq
            ) ORDER BY ss.seq, ss.id
        ) FILTER (WHERE ss.id IS NOT NULL), '[]')
    FROM dataflow.stacks s
    LEFT JOIN dataflow.stack_sources ss ON ss.stack_name = s.name
    WHERE s.name = p_name
    GROUP BY s.name, s.label, s.fields, s.amount_field, s.date_field, s.balance_offset, s.created_at;
$$ 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,
    p_amount_field    TEXT DEFAULT NULL,
    p_date_field      TEXT DEFAULT NULL
) RETURNS dataflow.stack_sources AS $$
    INSERT INTO dataflow.stack_sources (stack_name, source_name, field_map, amount_sign, balance_offset, amount_field, date_field, seq)
    VALUES (
        p_stack_name, p_source_name, p_field_map, p_amount_sign, p_balance_offset, p_amount_field, p_date_field,
        (SELECT COALESCE(MAX(seq), 0) + 1 FROM dataflow.stack_sources WHERE stack_name = p_stack_name)
    )
    ON CONFLICT (stack_name, source_name) DO UPDATE SET
        field_map       = EXCLUDED.field_map,
        amount_sign     = EXCLUDED.amount_sign,
        balance_offset  = EXCLUDED.balance_offset,
        amount_field    = EXCLUDED.amount_field,
        date_field      = EXCLUDED.date_field
    RETURNING *;
$$ 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
-- Queries dfv.{source} directly using per-source amount/date fields.
-- No stack view required.
------------------------------------------------------
CREATE OR REPLACE FUNCTION calibrate_balance(
    p_stack_name    TEXT,
    p_source_name   TEXT,
    p_as_of_date    DATE,
    p_known_balance NUMERIC
) RETURNS JSON AS $$
DECLARE
    v_src       dataflow.stack_sources%ROWTYPE;
    v_running   NUMERIC;
    v_sql       TEXT;
BEGIN
    SELECT * INTO v_src
    FROM dataflow.stack_sources
    WHERE stack_name = p_stack_name AND source_name = p_source_name;

    IF NOT FOUND THEN
        RETURN json_build_object('success', false, 'error', 'Source not in stack');
    END IF;
    IF v_src.amount_field IS NULL OR v_src.date_field IS NULL THEN
        RETURN json_build_object('success', false, 'error', 'Set amount and date fields on this source first');
    END IF;

    BEGIN
        IF p_as_of_date IS NULL THEN
            v_sql := format(
                'SELECT COALESCE(SUM(%I * %s), 0) FROM dfv.%I',
                v_src.amount_field, v_src.amount_sign, p_source_name
            );
        ELSE
            v_sql := format(
                'SELECT COALESCE(SUM(%I * %s), 0) FROM dfv.%I WHERE %I <= %L::date',
                v_src.amount_field, v_src.amount_sign, p_source_name, v_src.date_field, p_as_of_date
            );
        END IF;
        EXECUTE v_sql INTO v_running;
    EXCEPTION WHEN undefined_table THEN
        RETURN json_build_object('success', false, 'error', 'Source view not found — generate the source view first');
    END;

    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,
        'suggested_offset', p_known_balance - v_running
    );
END;
$$ LANGUAGE plpgsql STABLE;

------------------------------------------------------
-- Function: generate_stack_view
-- Builds a WITH ... UNION ALL view in dfv schema from existing dfv source views.
-- Each source CTE applies amount_sign and computes a per-source running balance.
-- Outer SELECT adds net_balance across all sources.
------------------------------------------------------
CREATE OR REPLACE FUNCTION generate_stack_view(p_stack_name TEXT, p_dry_run BOOLEAN DEFAULT false)
RETURNS JSON AS $$
DECLARE
    v_stack      dataflow.stacks%ROWTYPE;
    v_src        dataflow.stack_sources%ROWTYPE;
    v_field      JSONB;
    v_ctes       TEXT[] := '{}';
    v_cte_names  TEXT[] := '{}';
    v_select     TEXT;
    v_col        TEXT;
    v_src_field  TEXT;
    v_amt_src    TEXT;
    v_date_src   TEXT;
    v_view          TEXT;
    v_sql           TEXT;
    v_has_bal       BOOLEAN;
    v_canon_cols    TEXT;
    v_src_bal_cols  TEXT;
    v_total_offset  NUMERIC := 0;
    v_cascade_stale TEXT[];
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 CTE per source querying dfv.{source} directly
    FOR v_src IN
        SELECT * FROM dataflow.stack_sources WHERE stack_name = p_stack_name ORDER BY seq, id
    LOOP
        v_select := format('SELECT %L AS _source, id AS _id', v_src.source_name);

        FOR v_field IN SELECT * FROM jsonb_array_elements(v_stack.fields)
        LOOP
            v_col := v_field->>'name';

            IF v_has_bal AND v_col = v_stack.amount_field THEN
                -- Use per-source amount_field with sign applied
                IF v_src.amount_field IS NULL THEN
                    v_select := v_select || format(', NULL::%s AS %I', v_field->>'type', v_col);
                ELSE
                    v_select := v_select || format(', %I * %s AS %I', v_src.amount_field, v_src.amount_sign, v_col);
                END IF;
            ELSIF v_has_bal AND v_col = v_stack.date_field THEN
                -- Use per-source date_field
                IF v_src.date_field IS NULL THEN
                    v_select := v_select || format(', NULL::date AS %I', v_col);
                ELSE
                    v_select := v_select || format(', %I AS %I', v_src.date_field, v_col);
                END IF;
            ELSE
                -- Other canonical fields: use field_map or same name, NULL if column doesn't exist
                v_src_field := COALESCE(v_src.field_map->>v_col, v_col);
                IF EXISTS (
                    SELECT 1 FROM information_schema.columns
                    WHERE table_schema = 'dfv'
                      AND table_name = v_src.source_name
                      AND column_name = v_src_field
                ) THEN
                    v_select := v_select || format(', %I AS %I', v_src_field, v_col);
                ELSE
                    v_select := v_select || format(', NULL::text AS %I', v_col);
                END IF;
            END IF;
        END LOOP;

        v_select := v_select || format(' FROM dfv.%I', v_src.source_name);

        v_ctes      := v_ctes      || format('%I AS (%s)', v_src.source_name, v_select);
        v_cte_names := v_cte_names || quote_ident(v_src.source_name);

        -- Accumulate carried-forward source balance column and total offset
        IF v_has_bal THEN
            IF v_src_bal_cols IS NOT NULL THEN v_src_bal_cols := v_src_bal_cols || ', '; END IF;
            v_src_bal_cols := COALESCE(v_src_bal_cols, '') || format(
                'SUM(CASE WHEN _source = %L THEN %I END) OVER (ORDER BY %I ASC, _id ASC) + %s AS %I',
                v_src.source_name, v_stack.amount_field, v_stack.date_field,
                v_src.balance_offset, v_src.source_name || '_balance'
            );
            v_total_offset := v_total_offset + v_src.balance_offset;
        END IF;
    END LOOP;

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

    v_view := 'dfv.' || quote_ident(p_stack_name);

    v_canon_cols := (
        SELECT string_agg(quote_ident(f->>'name'), ', ')
        FROM jsonb_array_elements(v_stack.fields) f
    );

    IF v_has_bal THEN
        v_sql := format(
            'CREATE VIEW %s AS '
            'WITH %s, _stacked AS (SELECT * FROM %s) '
            'SELECT _source, _id, %s, '
            '%s, '
            'SUM(%I) OVER (ORDER BY %I ASC, _id ASC) + %s AS net_balance '
            'FROM _stacked ORDER BY %I DESC, _id DESC',
            v_view,
            array_to_string(v_ctes, ', '),
            array_to_string(v_cte_names, ' UNION ALL SELECT * FROM '),
            v_canon_cols,
            v_src_bal_cols,
            v_stack.amount_field,
            v_stack.date_field,
            v_total_offset,
            v_stack.date_field
        );
    ELSE
        v_sql := format(
            'CREATE VIEW %s AS '
            'WITH %s, _stacked AS (SELECT * FROM %s) '
            'SELECT _source, _id, %s FROM _stacked',
            v_view,
            array_to_string(v_ctes, ', '),
            array_to_string(v_cte_names, ' UNION ALL SELECT * FROM '),
            v_canon_cols
        );
    END IF;

    IF NOT p_dry_run THEN
        CREATE SCHEMA IF NOT EXISTS dfv;
        EXECUTE format('DROP VIEW IF EXISTS %s CASCADE', v_view);
        EXECUTE v_sql;

        -- Detect stacks whose views were dropped by CASCADE and mark them stale
        SELECT array_agg(s.name) INTO v_cascade_stale
        FROM dataflow.stacks s
        WHERE s.name != p_stack_name
          AND s.view_generated_at IS NOT NULL
          AND NOT EXISTS (
              SELECT 1 FROM pg_views v
              WHERE v.schemaname = 'dfv' AND v.viewname = s.name
          );

        UPDATE dataflow.stacks SET view_generated_at = NULL
        WHERE name = ANY(v_cascade_stale);
    END IF;

    RETURN json_build_object(
        'success', true,
        'view', v_view,
        'sql', v_sql,
        'cascade_stale', COALESCE(to_json(v_cascade_stale), '[]'::json)
    );
END;
$$ LANGUAGE plpgsql;

------------------------------------------------------
-- Function: get_stack_balance
-- Returns the current running balance (last row of the generated view)
------------------------------------------------------
CREATE OR REPLACE FUNCTION get_stack_balance(p_stack_name TEXT)
RETURNS JSON AS $$
DECLARE
    v_stack     dataflow.stacks%ROWTYPE;
    v_balance   NUMERIC;
    v_view      TEXT;
    v_sql       TEXT;
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', 'amount_field and date_field must be set');
    END IF;

    v_view := 'dfv.' || quote_ident(p_stack_name);

    BEGIN
        v_sql := format(
            'SELECT net_balance FROM %s ORDER BY %I DESC, _id DESC LIMIT 1',
            v_view, v_stack.date_field
        );
        EXECUTE v_sql INTO v_balance;
    EXCEPTION WHEN undefined_table THEN
        RETURN json_build_object('success', false, 'error', 'View not generated yet — click Generate first');
    END;

    RETURN json_build_object('success', true, 'balance', v_balance);
END;
$$ LANGUAGE plpgsql STABLE;

COMMENT ON FUNCTION generate_stack_view(TEXT, BOOLEAN) IS 'Generate a UNION ALL view in dfv schema combining multiple sources with optional running balance; p_dry_run=true returns SQL without executing';
COMMENT ON FUNCTION calibrate_balance IS 'Given a known good balance at a date, compute the offset to add to balance_offset';
COMMENT ON FUNCTION get_stack_balance IS 'Return the current running balance (last row) from the generated dfv view';

------------------------------------------------------
-- Function: reorder_stack_sources
------------------------------------------------------
CREATE OR REPLACE FUNCTION reorder_stack_sources(p_stack_name TEXT, p_source_names TEXT[])
RETURNS VOID AS $$
DECLARE
    i INTEGER;
BEGIN
    FOR i IN 1..array_length(p_source_names, 1) LOOP
        UPDATE dataflow.stack_sources
        SET seq = i
        WHERE stack_name = p_stack_name AND source_name = p_source_names[i];
    END LOOP;
END;
$$ LANGUAGE plpgsql;