const express = require('express');
const { applyTokens, buildWhere, buildExcludeClause, buildSetClause, esc } = require('../lib/sql_generator');
const { fcTable } = require('../lib/utils');

module.exports = function(pool) {
    const router = express.Router();

    async function runSQL(sql) {
        console.log('--- SQL ---\n', sql, '\n--- END SQL ---');
        return pool.query(sql);
    }

    // fetch everything needed to execute an operation:
    // version + source info, col_meta, fc_table name, stored SQL
    async function getContext(versionId, operation) {
        const verResult = await pool.query(`
            SELECT v.*, s.schema, s.tname, s.id AS source_id
            FROM pf.version v
            JOIN pf.source s ON s.id = v.source_id
            WHERE v.id = $1
        `, [versionId]);
        if (verResult.rows.length === 0) {
            const err = new Error('Version not found'); err.status = 404; throw err;
        }
        const version = verResult.rows[0];

        const colResult = await pool.query(
            `SELECT * FROM pf.col_meta WHERE source_id = $1 ORDER BY opos`,
            [version.source_id]
        );
        const colMeta  = colResult.rows;
        const dimCols  = colMeta.filter(c => c.role === 'dimension').map(c => c.cname);
        const valueCol = colMeta.find(c => c.role === 'value')?.cname;
        const unitsCol = colMeta.find(c => c.role === 'units')?.cname;

        const sqlResult = await pool.query(
            `SELECT sql FROM pf.sql WHERE source_id = $1 AND operation = $2`,
            [version.source_id, operation]
        );
        if (sqlResult.rows.length === 0) {
            const err = new Error(`No generated SQL for operation "${operation}" — run generate-sql first`);
            err.status = 400; throw err;
        }

        return {
            version,
            table: fcTable(version.tname, version.id),
            colMeta,
            dimCols,
            valueCol,
            unitsCol,
            sql: sqlResult.rows[0].sql
        };
    }

    function guardOpen(version, res) {
        if (version.status === 'closed') {
            res.status(403).json({ error: 'Version is closed' });
            return false;
        }
        return true;
    }

    // fetch all rows for a version (all iters including reference)
    router.get('/versions/:id/data', async (req, res) => {
        try {
            const ctx = await getContext(parseInt(req.params.id), 'get_data');
            const sql = applyTokens(ctx.sql, { fc_table: ctx.table });
            const result = await runSQL(sql);
            res.json(result.rows);
        } catch (err) {
            console.error(err);
            res.status(err.status || 500).json({ error: err.message });
        }
    });

    // load baseline rows from source table for a date range
    // deletes existing iter='baseline' rows before inserting (handled inside stored SQL)
    router.post('/versions/:id/baseline', async (req, res) => {
        const { date_from, date_to, pf_user, note, replay } = req.body;
        if (!date_from || !date_to) {
            return res.status(400).json({ error: 'date_from and date_to are required' });
        }
        if (replay) {
            return res.status(501).json({ error: 'replay is not yet implemented' });
        }
        try {
            const ctx = await getContext(parseInt(req.params.id), 'baseline');
            if (!guardOpen(ctx.version, res)) return;

            const sql = applyTokens(ctx.sql, {
                fc_table:   ctx.table,
                version_id: ctx.version.id,
                pf_user:    esc(pf_user  || ''),
                note:       esc(note     || ''),
                params:     esc(JSON.stringify({ date_from, date_to })),
                date_from:  esc(date_from),
                date_to:    esc(date_to)
            });

            const result = await runSQL(sql);
            res.json({ rows_affected: result.rows.length });
        } catch (err) {
            console.error(err);
            res.status(err.status || 500).json({ error: err.message });
        }
    });

    // load reference rows from source table (additive — does not clear prior reference rows)
    router.post('/versions/:id/reference', async (req, res) => {
        const { date_from, date_to, pf_user, note } = req.body;
        if (!date_from || !date_to) {
            return res.status(400).json({ error: 'date_from and date_to are required' });
        }
        try {
            const ctx = await getContext(parseInt(req.params.id), 'reference');
            if (!guardOpen(ctx.version, res)) return;

            const sql = applyTokens(ctx.sql, {
                fc_table:   ctx.table,
                version_id: ctx.version.id,
                pf_user:    esc(pf_user  || ''),
                note:       esc(note     || ''),
                params:     esc(JSON.stringify({ date_from, date_to })),
                date_from:  esc(date_from),
                date_to:    esc(date_to)
            });

            const result = await runSQL(sql);
            res.json({ rows: result.rows, rows_affected: result.rows.length });
        } catch (err) {
            console.error(err);
            res.status(err.status || 500).json({ error: err.message });
        }
    });

    // scale a slice — adjust value and/or units by absolute amount or percentage
    router.post('/versions/:id/scale', async (req, res) => {
        const { pf_user, note, slice, value_incr, units_incr, pct } = req.body;
        if (!slice || Object.keys(slice).length === 0) {
            return res.status(400).json({ error: 'slice is required' });
        }
        try {
            const ctx = await getContext(parseInt(req.params.id), 'scale');
            if (!guardOpen(ctx.version, res)) return;

            const whereClause   = buildWhere(slice, ctx.dimCols);
            const excludeClause = buildExcludeClause(ctx.version.exclude_iters);

            let absValueIncr = value_incr || 0;
            let absUnitsIncr = units_incr || 0;

            // pct mode: run a quick totals query, convert percentages to absolutes
            if (pct && (value_incr || units_incr)) {
                const totals = await pool.query(`
                    SELECT
                        sum("${ctx.valueCol}") AS total_value,
                        sum("${ctx.unitsCol}") AS total_units
                    FROM ${ctx.table}
                    WHERE ${whereClause}
                    ${excludeClause}
                `);
                const { total_value, total_units } = totals.rows[0];
                if (value_incr) absValueIncr = (parseFloat(total_value) || 0) * value_incr / 100;
                if (units_incr) absUnitsIncr = (parseFloat(total_units) || 0) * units_incr / 100;
            }

            if (absValueIncr === 0 && absUnitsIncr === 0) {
                return res.status(400).json({ error: 'value_incr and/or units_incr must be non-zero' });
            }

            const sql = applyTokens(ctx.sql, {
                fc_table:       ctx.table,
                version_id:     ctx.version.id,
                pf_user:        esc(pf_user || ''),
                note:           esc(note    || ''),
                params:         esc(JSON.stringify({ slice, value_incr, units_incr, pct })),
                slice:          esc(JSON.stringify(slice)),
                where_clause:   whereClause,
                exclude_clause: excludeClause,
                value_incr:     absValueIncr,
                units_incr:     absUnitsIncr
            });

            const result = await runSQL(sql);
            res.json({ rows: result.rows, rows_affected: result.rows.length });
        } catch (err) {
            console.error(err);
            res.status(err.status || 500).json({ error: err.message });
        }
    });

    // recode dimension values on a slice
    // inserts negative rows to zero out the original, positive rows with new dimension values
    router.post('/versions/:id/recode', async (req, res) => {
        const { pf_user, note, slice, set } = req.body;
        if (!slice || Object.keys(slice).length === 0) return res.status(400).json({ error: 'slice is required' });
        if (!set   || Object.keys(set).length   === 0) return res.status(400).json({ error: 'set is required' });

        try {
            const ctx = await getContext(parseInt(req.params.id), 'recode');
            if (!guardOpen(ctx.version, res)) return;

            const whereClause   = buildWhere(slice, ctx.dimCols);
            const excludeClause = buildExcludeClause(ctx.version.exclude_iters);
            const setClause     = buildSetClause(ctx.dimCols, set);

            const sql = applyTokens(ctx.sql, {
                fc_table:       ctx.table,
                version_id:     ctx.version.id,
                pf_user:        esc(pf_user || ''),
                note:           esc(note    || ''),
                params:         esc(JSON.stringify({ slice, set })),
                slice:          esc(JSON.stringify(slice)),
                where_clause:   whereClause,
                exclude_clause: excludeClause,
                set_clause:     setClause
            });

            const result = await runSQL(sql);
            res.json({ rows: result.rows, rows_affected: result.rows.length });
        } catch (err) {
            console.error(err);
            res.status(err.status || 500).json({ error: err.message });
        }
    });

    // clone a slice as new business under new dimension values
    // does not offset the original slice
    router.post('/versions/:id/clone', async (req, res) => {
        const { pf_user, note, slice, set, scale } = req.body;
        if (!slice || Object.keys(slice).length === 0) return res.status(400).json({ error: 'slice is required' });
        if (!set   || Object.keys(set).length   === 0) return res.status(400).json({ error: 'set is required' });

        try {
            const ctx = await getContext(parseInt(req.params.id), 'clone');
            if (!guardOpen(ctx.version, res)) return;

            const scaleFactor   = (scale != null) ? parseFloat(scale) : 1.0;
            const whereClause   = buildWhere(slice, ctx.dimCols);
            const excludeClause = buildExcludeClause(ctx.version.exclude_iters);
            const setClause     = buildSetClause(ctx.dimCols, set);

            const sql = applyTokens(ctx.sql, {
                fc_table:       ctx.table,
                version_id:     ctx.version.id,
                pf_user:        esc(pf_user || ''),
                note:           esc(note    || ''),
                params:         esc(JSON.stringify({ slice, set, scale: scaleFactor })),
                slice:          esc(JSON.stringify(slice)),
                where_clause:   whereClause,
                exclude_clause: excludeClause,
                set_clause:     setClause,
                scale_factor:   scaleFactor
            });

            const result = await runSQL(sql);
            res.json({ rows: result.rows, rows_affected: result.rows.length });
        } catch (err) {
            console.error(err);
            res.status(err.status || 500).json({ error: err.message });
        }
    });

    return router;
};