// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package postgres

import (
	"context"
	"database/sql"
	"fmt"

	"github.com/Masterminds/squirrel"
	"github.com/lib/pq"
	"golang.org/x/pkgsite/internal"
	"golang.org/x/pkgsite/internal/derrors"
	"golang.org/x/pkgsite/internal/version"
)

// UpsertVersionMap inserts a version_map entry into the database.
func (db *DB) UpsertVersionMap(ctx context.Context, vm *internal.VersionMap) (err error) {
	defer derrors.WrapStack(&err, "DB.UpsertVersionMap(ctx, tx, %q, %q, %q)",
		vm.ModulePath, vm.RequestedVersion, vm.ResolvedVersion)

	var moduleID int
	if vm.ResolvedVersion != "" {
		if err := db.db.QueryRow(ctx, `SELECT id FROM modules WHERE module_path=$1 AND version=$2`,
			vm.ModulePath, vm.ResolvedVersion).Scan(&moduleID); err != nil && err != sql.ErrNoRows {
			return err
		}
	}

	var sortVersion string
	if vm.ResolvedVersion != "" {
		sortVersion = version.ForSorting(vm.ResolvedVersion)
	}
	_, err = db.db.Exec(ctx,
		`INSERT INTO version_map(
				module_path,
				requested_version,
				resolved_version,
				go_mod_path,
				status,
				error,
				sort_version,
				module_id)
			VALUES($1,$2,$3,$4,$5,$6,$7,$8)
			ON CONFLICT (module_path, requested_version)
			DO UPDATE SET
				module_path=excluded.module_path,
				go_mod_path=excluded.go_mod_path,
				requested_version=excluded.requested_version,
				resolved_version=excluded.resolved_version,
				status=excluded.status,
				error=excluded.error,
				sort_version=excluded.sort_version,
				module_id=excluded.module_id`,
		vm.ModulePath,
		vm.RequestedVersion,
		vm.ResolvedVersion,
		vm.GoModPath,
		vm.Status,
		vm.Error,
		sortVersion,
		moduleID)
	return err
}

// GetVersionMap fetches a version_map entry corresponding to the given
// modulePath and requestedVersion.
func (db *DB) GetVersionMap(ctx context.Context, modulePath, requestedVersion string) (_ *internal.VersionMap, err error) {
	defer derrors.WrapStack(&err, "DB.GetVersionMap(ctx, tx, %q, %q)", modulePath, requestedVersion)
	if modulePath == internal.UnknownModulePath {
		return nil, fmt.Errorf("modulePath must be specified: %w", derrors.InvalidArgument)
	}

	q, args, err := versionMapSelect().
		Where(squirrel.Eq{"module_path": modulePath}).
		Where(squirrel.Eq{"requested_version": requestedVersion}).
		PlaceholderFormat(squirrel.Dollar).ToSql()
	if err != nil {
		return nil, err
	}
	var vm internal.VersionMap
	err = db.db.QueryRow(ctx, q, args...).Scan(
		&vm.ModulePath, &vm.RequestedVersion, &vm.ResolvedVersion, &vm.GoModPath,
		&vm.Status, &vm.Error, &vm.UpdatedAt)
	switch err {
	case nil:
		return &vm, nil
	case sql.ErrNoRows:
		return nil, derrors.NotFound
	default:
		return nil, err
	}
}

// GetVersionMaps returns all of the version maps for the provided
// path and requested version if they are present.
func (db *DB) GetVersionMaps(ctx context.Context, paths []string, requestedVersion string) (_ []*internal.VersionMap, err error) {
	defer derrors.WrapStack(&err, "DB.GetVersionMapsWith4xxStatus(ctx, %v, %q)", paths, requestedVersion)

	var result []*internal.VersionMap
	versionMaps := map[string]*internal.VersionMap{}
	collect := func(rows *sql.Rows) error {
		var vm internal.VersionMap
		if err := rows.Scan(
			&vm.ModulePath, &vm.RequestedVersion, &vm.ResolvedVersion, &vm.GoModPath,
			&vm.Status, &vm.Error, &vm.UpdatedAt); err != nil {
			return err
		}
		if _, ok := versionMaps[vm.ModulePath]; !ok {
			versionMaps[vm.ModulePath] = &vm
			result = append(result, &vm)
		}
		return nil
	}
	q, args, err := versionMapSelect().
		Where("module_path = ANY(?)", pq.Array(paths)).
		Where(squirrel.Or{squirrel.Eq{"requested_version": requestedVersion}, squirrel.Eq{"resolved_version": requestedVersion}}).
		OrderBy("module_path DESC").
		PlaceholderFormat(squirrel.Dollar).ToSql()
	if err != nil {
		return nil, fmt.Errorf("squirrel.ToSql: %v", err)
	}
	if err := db.db.RunQuery(ctx, q, collect, args...); err != nil {
		return nil, err
	}
	return result, nil
}

func versionMapSelect() squirrel.SelectBuilder {
	return squirrel.Select(
		"module_path",
		"requested_version",
		"resolved_version",
		"go_mod_path",
		"status",
		"error",
		"updated_at",
	).From("version_map")
}