// Copyright 2023 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package commands

import (
	"bytes"
	"context"
	"fmt"
	"strconv"
	"strings"

	"github.com/dolthub/go-mysql-server/sql"
	"github.com/gocraft/dbr/v2"
	"github.com/gocraft/dbr/v2/dialect"

	"github.com/dolthub/dolt/go/cmd/dolt/cli"
	"github.com/dolthub/dolt/go/cmd/dolt/errhand"
	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
	"github.com/dolthub/dolt/go/libraries/doltcore/env"
	"github.com/dolthub/dolt/go/libraries/doltcore/ref"
	"github.com/dolthub/dolt/go/libraries/utils/argparser"
	eventsapi "github.com/dolthub/eventsapi_schema/dolt/services/eventsapi/v1alpha1"
)

const (
	PushCmdRef  = "push"
	PopCmdRef   = "pop"
	DropCmdRef  = "drop"
	ApplyCmdRef = "apply"
	ClearCmdRef = "clear"
	ListCmdRef  = "list"
)

var stashDocs = cli.CommandDocumentationContent{
	ShortDesc: "Stash the changes in a dirty workspace away.",
	LongDesc: `Use dolt stash when you want to record the current state of the workspace and the index, but want to go back to a clean workspace.

The command saves your local modifications away and reverts the workspace to match the HEAD commit. The stash entries that are saved away can be listed with {{.EmphasisLeft}}dolt stash list{{.EmphasisRight}}.

With {{.EmphasisLeft}}pop{{.EmphasisRight}}, the stash entry is applied to the working set and then removed. With {{.EmphasisLeft}}apply{{.EmphasisRight}}, the stash entry is applied but kept. Both default to {{.EmphasisLeft}}stash@{0}{{.EmphasisRight}} if no stash is specified. If there are conflicting local changes, the operation fails and the stash entry is preserved.

Stash entries are shared across branches, so you can stash on one branch and pop or apply on another.
`,
	Synopsis: []string{
		"", // this is for `dolt stash` itself.
		"list",
		"pop [{{.LessThan}}stash{{.GreaterThan}}]",
		"apply [{{.LessThan}}stash{{.GreaterThan}}]",
		"drop [{{.LessThan}}stash{{.GreaterThan}}]",
		"clear",
	},
}

type StashCmd struct{}

// Name returns the name of the Dolt cli command. This is what is used on the command line to invoke the command
func (cmd StashCmd) Name() string {
	return "stash"
}

// Description returns a description of the command
func (cmd StashCmd) Description() string {
	return "Stash the changes in a dirty workspace away."
}

func (cmd StashCmd) Docs() *cli.CommandDocumentation {
	ap := cmd.ArgParser()
	return cli.NewCommandDocumentation(stashDocs, ap)
}

func (cmd StashCmd) ArgParser() *argparser.ArgParser {
	return cli.CreateStashArgParser()
}

// EventType returns the type of the event to log
func (cmd StashCmd) EventType() eventsapi.ClientEventType {
	return eventsapi.ClientEventType_STASH
}

// Exec executes the command
func (cmd StashCmd) Exec(ctx context.Context, commandStr string, args []string, _ *env.DoltEnv, cliCtx cli.CliContext) int {
	ap := cli.CreateStashArgParser()

	apr, _, terminate, status := ParseArgsOrPrintHelp(ap, commandStr, args, stashDocs)
	if terminate {
		return status
	}
	if len(apr.Args) > 2 {
		cli.PrintErrln(fmt.Errorf("dolt stash takes 2 arguments, received %d", len(apr.Args)))
		return 1
	}

	subcommand := "push"
	if len(apr.Args) > 0 {
		subcommand = strings.ToLower(apr.Arg(0))
	}

	queryist, err := cliCtx.QueryEngine(ctx)
	if err != nil {
		cli.PrintErrln(errhand.VerboseErrorFromError(err))
		return 1
	}

	idx := 0
	if apr.NArg() > 1 {
		idx, err = parseStashIndex(apr.Arg(1))
		if err != nil {
			cli.PrintErrln(errhand.VerboseErrorFromError(err))
			return 1
		}
	}

	// List queries a system table, unlike the procedure the other commands use, so we handle it in a special case
	if subcommand == ListCmdRef {
		return stashList(ctx, cliCtx)
	}

	// Pre-query: Pop, Apply, and Drop commands need to confirm that the given id is valid.
	// We'll also check that the subcommand is valid
	var stash *doltdb.Stash
	switch subcommand {
	case PopCmdRef, ApplyCmdRef, DropCmdRef:
		stash, err = validateStashAtIdx(queryist.Queryist, queryist.Context, idx)
		if err != nil {
			cli.PrintErrln(errhand.VerboseErrorFromError(err))
			return 1
		}
	case PushCmdRef, ClearCmdRef:
	default:
		err = fmt.Errorf("unknown stash subcommand %s", subcommand)
		cli.PrintErrln(errhand.VerboseErrorFromError(err))
		return 1
	}

	// Now build the call to DOLT_STASH and run it
	interpolatedQuery, err := generateStashSql(apr, subcommand)
	if err != nil {
		cli.PrintErrln(errhand.VerboseErrorFromError(err))
		return 1
	}
	_, rowIter, _, err := queryist.Queryist.Query(queryist.Context, interpolatedQuery)
	if err != nil {
		cli.PrintErrln(errhand.VerboseErrorFromError(err))
		if strings.Contains(err.Error(), "No local changes to save") {
			return 0
		}
		return 1
	}

	// Finally, print out any relevant status message and consume the row iterator
	switch subcommand {
	case PushCmdRef:
		stashes, err := getStashesSQL(queryist.Context, queryist.Queryist, 1)
		if err != nil {
			cli.PrintErrln(errhand.VerboseErrorFromError(err))
			return 1
		}
		stash := stashes[0]
		cli.Println(fmt.Sprintf("Saved working directory and index state WIP on %s: %s %s", stash.BranchReference, stash.CommitHash, stash.Description))
	case PopCmdRef:
		err = PrintStatus(queryist.Context, false, cliCtx)
		if err != nil {
			cli.Println("The stash entry is kept in case you need it again.")
			cli.PrintErrln(errhand.VerboseErrorFromError(err))
			return 1
		}
		cli.Println(fmt.Sprintf("Dropped refs/stash@{%v} (%s)", idx, stash.CommitHash))
	case DropCmdRef:
		cli.Println(fmt.Sprintf("Dropped refs/stash@{%v} (%s)", idx, stash.CommitHash))
	case ApplyCmdRef:
		err = PrintStatus(queryist.Context, false, cliCtx)
		if err != nil {
			cli.Println("The stash entry is kept in case you need it again.")
			cli.PrintErrln(errhand.VerboseErrorFromError(err))
			return 1
		}
	}

	_, err = sql.RowIterToRows(queryist.Context, rowIter)

	if err != nil {
		cli.PrintErrln(errhand.VerboseErrorFromError(err))
		return 1
	}
	return 0
}

// validateStashAtIdx verifies that the given number is within the range of stashes, then returns the stash at that id.
func validateStashAtIdx(queryist cli.Queryist, sqlCtx *sql.Context, idx int) (*doltdb.Stash, error) {
	stashes, err := getStashesSQL(sqlCtx, queryist, 0)
	if err != nil {
		return nil, err
	}
	if len(stashes) == 0 {
		return nil, fmt.Errorf("no stash entries found")
	}
	if len(stashes)-1 < idx {
		return nil, fmt.Errorf("stash index stash@{%d} does not exist", idx)
	}

	return stashes[idx], nil
}
func stashList(ctx context.Context, cliCtx cli.CliContext) int {
	queryist, err := cliCtx.QueryEngine(ctx)
	if err != nil {
		cli.PrintErrln(errhand.VerboseErrorFromError(err))
		return 1
	}

	stashes, err := getStashesSQL(queryist.Context, queryist.Queryist, 0)
	if err != nil {
		cli.PrintErrln(errhand.VerboseErrorFromError(err))
		return 1
	}
	for _, stash := range stashes {
		cli.Println(fmt.Sprintf("%s: WIP on %s: %s %s", stash.Name, stash.BranchReference, stash.CommitHash, stash.Description))
	}

	return 0
}

// getStashesSQL queries the dolt_stashes system table to return the requested number of stashes. A limit of 0 will get all stashes
func getStashesSQL(sqlCtx *sql.Context, queryist cli.Queryist, limit int) ([]*doltdb.Stash, error) {
	limitStr := fmt.Sprintf("limit %d", limit)
	if limit == 0 {
		limitStr = ""
	}

	qry := fmt.Sprintf("select stash_id, branch, hash, commit_message from dolt_stashes where name = '%s' order by stash_id ASC %s;", doltdb.DoltCliRef, limitStr)
	rows, err := cli.GetRowsForSql(queryist, sqlCtx, qry)
	if err != nil {
		return nil, err
	}

	var stashes []*doltdb.Stash
	for _, s := range rows {
		id, ok := s[0].(string)
		if !ok {
			return nil, fmt.Errorf("Invalid stash id")
		}

		branch, ok := s[1].(string)
		if !ok {
			return nil, fmt.Errorf("invalid stash branch")
		}
		fullBranch := ref.NewBranchRef(branch).String()

		stashHash, ok := s[2].(string)
		if !ok {
			return nil, fmt.Errorf("invalid stash hash")
		}

		msg, ok := s[3].(string)
		if !ok {
			return nil, fmt.Errorf("invalid stash message")
		}

		stashes = append(stashes, &doltdb.Stash{
			Name:            id,
			BranchReference: fullBranch,
			Description:     msg,
			CommitHash:      stashHash,
		})
	}

	return stashes, nil
}

// generateStashSql returns the query that will call the `DOLT_STASH` stored procedure.
func generateStashSql(apr *argparser.ArgParseResults, subcommand string) (string, error) {
	var buffer bytes.Buffer
	var params []interface{}
	buffer.WriteString("CALL DOLT_STASH(?, ?")
	params = append(params, subcommand)
	params = append(params, doltdb.DoltCliRef)

	if len(apr.Args) == 2 {
		params = append(params, apr.Arg(1))
		buffer.WriteString(", ?")
	}

	if apr.Contains(cli.AllFlag) {
		buffer.WriteString(", '--all'")
	}
	if apr.Contains(cli.IncludeUntrackedFlag) {
		buffer.WriteString(", '--include-untracked'")
	}

	buffer.WriteString(")")
	interpolatedQuery, err := dbr.InterpolateForDialect(buffer.String(), params, dialect.MySQL)
	return interpolatedQuery, err
}

func parseStashIndex(stashID string) (int, error) {
	var err error
	stashID = strings.TrimSuffix(strings.TrimPrefix(stashID, "stash@{"), "}")
	idx, err := strconv.Atoi(stashID)
	if err != nil {
		return 0, fmt.Errorf("error: %s is not a valid reference", stashID)
	}

	return idx, nil
}