// This is Free Software under GNU Affero General Public License v >= 3.0
// without warranty, see README.md and license for details.
//
// SPDX-License-Identifier: AGPL-3.0-or-later
// License-Filename: LICENSES/AGPL-3.0.txt
//
// Copyright (C) 2018 by via donau
//   – Österreichische Wasserstraßen-Gesellschaft mbH
// Software engineering by Intevation GmbH
//
// Author(s):
//  * Sascha L. Teichmann <sascha.teichmann@intevation.de>

package controllers

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"strconv"
	"strings"

	"github.com/gorilla/mux"
	"github.com/jackc/pgx/pgtype"

	"gemma.intevation.de/gemma/pkg/auth"
	"gemma.intevation.de/gemma/pkg/imports"
	"gemma.intevation.de/gemma/pkg/models"
)

const (
	selectImportsSQL = `
SELECT
  id,
  state::varchar,
  enqueued,
  kind,
  username,
  signer,
  summary
FROM waterway.imports
`

	selectHasImportSQL = `
SELECT true FROM Waterway.imports WHERE id = $1`

	selectHasNoRunningImportSQL = `
SELECT true FROM waterway.imports
WHERE id = $1 AND state <> 'running'::waterway.import_state`

	selectImportLogsSQL = `
SELECT
  time,
  kind::varchar,
  msg
FROM waterway.import_logs
WHERE import_id = $1
ORDER BY time`

	deleteLogsSQL = `
DELETE FROM waterway.import_logs WHERE import_id = $1`

	deleteImportSQL = `
DELETE FROM waterway.imports WHERE id = $1`
)

func toTextArray(txt string, allowed []string) *pgtype.TextArray {
	parts := strings.Split(txt, ",")
	var accepted []string
	for _, part := range parts {
		if part = strings.ToLower(strings.TrimSpace(part)); len(part) == 0 {
			continue
		}
		for _, a := range allowed {
			if part == a {
				accepted = append(accepted, part)
				break
			}
		}
	}
	if len(accepted) == 0 {
		return nil
	}
	var ta pgtype.TextArray
	if err := ta.Set(accepted); err != nil {
		log.Printf("warn: %v\n", err)
		return nil
	}
	return &ta
}

func queryImportListStmt(
	conn *sql.Conn,
	req *http.Request,
) (*sql.Rows, error) {

	var (
		stmt   strings.Builder
		args   []interface{}
		states *pgtype.TextArray
		kinds  *pgtype.TextArray
	)

	arg := func(format string, v interface{}) {
		fmt.Fprintf(&stmt, format, len(args)+1)
		args = append(args, v)
	}

	if st := req.FormValue("states"); st != "" {
		states = toTextArray(st, imports.ImportStateNames)
	}

	if ks := req.FormValue("kinds"); ks != "" {
		kinds = toTextArray(ks, imports.ImportKindNames)
	}

	stmt.WriteString(selectImportsSQL)
	if states != nil || kinds != nil {
		stmt.WriteString(" WHERE ")
	}

	if states != nil {
		arg(" state = ANY($%d) ", states)
	}

	if states != nil && kinds != nil {
		stmt.WriteString("AND")
	}

	if kinds != nil {
		arg(" kind = ANY($%d) ", kinds)
	}

	stmt.WriteString(" ORDER BY enqueued DESC ")

	if lim := req.FormValue("limit"); lim != "" {
		limit, err := strconv.ParseInt(lim, 10, 64)
		if err != nil {
			return nil, err
		}
		arg(" LIMIT $%d ", limit)
	}

	if ofs := req.FormValue("offset"); ofs != "" {
		offset, err := strconv.ParseInt(ofs, 10, 64)
		if err != nil {
			return nil, err
		}
		arg(" OFFSET $%d ", offset)
	}

	return conn.QueryContext(req.Context(), stmt.String(), args...)
}

func listImports(
	_ interface{},
	req *http.Request,
	conn *sql.Conn,
) (jr JSONResult, err error) {

	var rows *sql.Rows
	rows, err = queryImportListStmt(conn, req)
	if err != nil {
		return
	}
	defer rows.Close()

	imports := make([]*models.Import, 0, 20)

	var signer, summary sql.NullString

	for rows.Next() {
		var it models.Import
		if err = rows.Scan(
			&it.ID,
			&it.State,
			&it.Enqueued,
			&it.Kind,
			&it.User,
			&signer,
			&summary,
		); err != nil {
			return
		}
		if signer.Valid {
			it.Signer = signer.String
		}
		if summary.Valid {
			if err = json.NewDecoder(
				strings.NewReader(summary.String)).Decode(&it.Summary); err != nil {
				return
			}
		}
		imports = append(imports, &it)
	}

	if err = rows.Err(); err != nil {
		return
	}

	jr = JSONResult{
		Result: struct {
			Imports []*models.Import `json:"imports"`
		}{
			Imports: imports,
		},
	}
	return
}

func importLogs(
	_ interface{},
	req *http.Request,
	conn *sql.Conn,
) (jr JSONResult, err error) {

	ctx := req.Context()

	id, _ := strconv.ParseInt(mux.Vars(req)["id"], 10, 64)

	// Check if he have such a import job first.
	var dummy bool
	err = conn.QueryRowContext(ctx, selectHasImportSQL, id).Scan(&dummy)
	switch {
	case err == sql.ErrNoRows:
		err = JSONError{
			Code:    http.StatusNotFound,
			Message: fmt.Sprintf("Cannot find import #%d.", id),
		}
		return
	case err != nil:
		return
	}

	// We have it -> generate log entries.
	var rows *sql.Rows
	rows, err = conn.QueryContext(ctx, selectImportLogsSQL, id)
	if err != nil {
		return
	}
	defer rows.Close()

	entries := make([]*models.ImportLogEntry, 0, 10)

	for rows.Next() {
		var entry models.ImportLogEntry
		if err = rows.Scan(&entry.Time, &entry.Kind, &entry.Message); err != nil {
			return
		}
		entries = append(entries, &entry)
	}

	if err = rows.Err(); err != nil {
		return
	}

	jr = JSONResult{
		Result: struct {
			Entries []*models.ImportLogEntry `json:"entries"`
		}{
			Entries: entries,
		},
	}
	return
}

func deleteImport(
	_ interface{},
	req *http.Request,
	conn *sql.Conn,
) (jr JSONResult, err error) {

	ctx := req.Context()
	id, _ := strconv.ParseInt(mux.Vars(req)["id"], 10, 64)

	var tx *sql.Tx
	tx, err = conn.BeginTx(ctx, nil)
	if err != nil {
		return
	}
	defer tx.Rollback()

	// Check if he have such a import job first.
	var dummy bool
	err = tx.QueryRowContext(ctx, selectHasNoRunningImportSQL, id).Scan(&dummy)
	switch {
	case err == sql.ErrNoRows:
		err = JSONError{
			Code:    http.StatusNotFound,
			Message: fmt.Sprintf("Cannot find import #%d.", id),
		}
		return
	case err != nil:
		return
	}

	if _, err = tx.ExecContext(ctx, deleteLogsSQL, id); err != nil {
		return
	}

	if _, err = tx.ExecContext(ctx, deleteImportSQL, id); err != nil {
		return
	}

	if err = tx.Commit(); err != nil {
		return
	}

	jr = JSONResult{Code: http.StatusNoContent}

	return
}

const (
	isPendingSQL = `
SELECT state = 'pending'::waterway.import_state, kind
FROM waterway.imports
WHERE id = $1`

	reviewSQL = `
UPDATE waterway.imports SET
  state = $1::waterway.import_state,
  signer = $2
WHERE id = $3`

	deleteImportDataSQL = `SELECT waterway.del_import($1)`

	deleteImportTrackSQL = `
DELETE FROM waterway.track_imports WHERE import_id = $1`

	logDecisionSQL = `
INSERT INTO waterway.import_logs (import_id, msg) VALUES ($1, $2)`
)

func reviewImports(
	reviews interface{},
	req *http.Request,
	conn *sql.Conn,
) (JSONResult, error) {

	rs := reviews.([]*models.Review)

	type reviewResult struct {
		ID      int64  `json:"id"`
		Message string `json:"message,omitempty"`
		Error   string `json:"error,omitempty"`
	}

	results := make([]reviewResult, len(rs))

	for i, rev := range rs {
		msg, err := decideImport(req, conn, rev.ID, string(rev.State))
		var errString string
		if err != nil {
			errString = err.Error()
		}
		results[i] = reviewResult{
			ID:      rev.ID,
			Message: msg,
			Error:   errString,
		}
	}

	return JSONResult{Result: results}, nil
}

func reviewImport(
	_ interface{},
	req *http.Request,
	conn *sql.Conn,
) (jr JSONResult, err error) {

	vars := mux.Vars(req)
	id, _ := strconv.ParseInt(vars["id"], 10, 64)
	state := vars["state"]

	var msg string
	if msg, err = decideImport(req, conn, id, state); err != nil {
		return
	}

	result := struct {
		Message string `json:"message"`
	}{
		Message: msg,
	}

	jr = JSONResult{Result: &result}
	return
}

func decideImport(
	req *http.Request,
	conn *sql.Conn,
	id int64,
	state string,
) (message string, err error) {
	ctx := req.Context()
	var tx *sql.Tx
	if tx, err = conn.BeginTx(ctx, nil); err != nil {
		return
	}
	defer tx.Rollback()

	var pending bool
	var kind string

	err = tx.QueryRowContext(ctx, isPendingSQL, id).Scan(&pending, &kind)
	switch {
	case err == sql.ErrNoRows:
		err = JSONError{
			Code:    http.StatusNotFound,
			Message: fmt.Sprintf("Cannot find import #%d.", id),
		}
		return
	case err != nil:
		return
	case !pending:
		err = JSONError{
			Code:    http.StatusBadRequest,
			Message: fmt.Sprintf("Import %d is not pending.", id),
		}
		return
	}

	if state == "accepted" {
		if jc := imports.FindJobCreator(imports.JobKind(kind)); jc != nil {
			if err = jc.StageDone(ctx, tx, id); err != nil {
				return
			}
		}

	} else {
		if _, err = tx.ExecContext(ctx, deleteImportDataSQL, id); err != nil {
			return
		}
	}

	// Remove the import track
	if _, err = tx.ExecContext(ctx, deleteImportTrackSQL, id); err != nil {
		return
	}

	// Log the decision and set the final state.
	session, _ := auth.GetSession(req)
	who := session.User

	if _, err = tx.ExecContext(ctx, logDecisionSQL, id,
		fmt.Sprintf("User '%s' %s import %d.", who, state, id)); err != nil {
		return
	}

	if _, err = tx.ExecContext(ctx, reviewSQL, state, who, id); err != nil {
		return
	}

	if err = tx.Commit(); err != nil {
		return
	}

	message = fmt.Sprintf(
		"Import #%d successfully changed to state '%s'.", id, state)

	return
}