package clidecision

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"iter"
	"os"
	"slices"
	"strings"
	"time"

	"github.com/jszwec/csvutil"
	log "github.com/sirupsen/logrus"
	"github.com/spf13/cobra"

	"github.com/crowdsecurity/go-cs-lib/ptr"

	"github.com/crowdsecurity/crowdsec/cmd/crowdsec-cli/args"
	"github.com/crowdsecurity/crowdsec/pkg/models"
	"github.com/crowdsecurity/crowdsec/pkg/types"
)

// decisionRaw is only used to unmarshall json/csv decisions
type decisionRaw struct {
	Duration string `csv:"duration,omitempty" json:"duration,omitempty"`
	Scenario string `csv:"reason,omitempty"   json:"reason,omitempty"`
	Scope    string `csv:"scope,omitempty"    json:"scope,omitempty"`
	Type     string `csv:"type,omitempty"     json:"type,omitempty"`
	Value    string `csv:"value"              json:"value"`
}

func parseDecisionList(content []byte, format string) ([]decisionRaw, error) {
	ret := []decisionRaw{}

	switch format {
	case "values":
		fmt.Fprintln(os.Stdout, "Parsing values")

		scanner := bufio.NewScanner(bytes.NewReader(content))
		for scanner.Scan() {
			value := strings.TrimSpace(scanner.Text())
			ret = append(ret, decisionRaw{Value: value})
		}

		if err := scanner.Err(); err != nil {
			return nil, fmt.Errorf("unable to parse values: '%w'", err)
		}
	case "json":
		fmt.Fprintln(os.Stdout, "Parsing json")

		if err := json.Unmarshal(content, &ret); err != nil {
			return nil, err
		}
	case "csv":
		fmt.Fprintln(os.Stdout, "Parsing csv")

		if err := csvutil.Unmarshal(content, &ret); err != nil {
			return nil, fmt.Errorf("unable to parse csv: '%w'", err)
		}
	default:
		return nil, fmt.Errorf("invalid format '%s', expected one of 'json', 'csv', 'values'", format)
	}

	return ret, nil
}

func excludeAllowlistedDecisions(decisions []*models.Decision, allowlistedValues []string) iter.Seq[*models.Decision] {
	return func(yield func(*models.Decision) bool) {
		for _, d := range decisions {
			if slices.Contains(allowlistedValues, *d.Value) {
				continue
			}

			if !yield(d) {
				return
			}
		}
	}
}

func (cli *cliDecisions) import_(ctx context.Context, input string, duration string, scope string, reason string, type_ string, batch int, format string) error {
	var (
		content []byte
		fin     *os.File
		err     error
	)

	if duration == "" {
		return errors.New("default duration cannot be empty")
	}

	if scope == "" {
		return errors.New("default scope cannot be empty")
	}

	if reason == "" {
		return errors.New("default reason cannot be empty")
	}

	if type_ == "" {
		return errors.New("default type cannot be empty")
	}

	// set format if the file has a json or csv extension
	if format == "" {
		if strings.HasSuffix(input, ".json") {
			format = "json"
		} else if strings.HasSuffix(input, ".csv") {
			format = "csv"
		}
	}

	if format == "" {
		return errors.New("unable to guess format from file extension, please provide a format with --format flag")
	}

	if input == "-" {
		fin = os.Stdin
		input = "stdin"
	} else {
		fin, err = os.Open(input)
		if err != nil {
			return fmt.Errorf("unable to open %s: %w", input, err)
		}
	}

	content, err = io.ReadAll(fin)
	if err != nil {
		return fmt.Errorf("unable to read from %s: %w", input, err)
	}

	decisionsListRaw, err := parseDecisionList(content, format)
	if err != nil {
		return err
	}

	if len(decisionsListRaw) == 0 {
		return errors.New("no decisions found")
	}

	decisions := make([]*models.Decision, len(decisionsListRaw))

	for i, d := range decisionsListRaw {
		if d.Value == "" {
			return fmt.Errorf("item %d: missing 'value'", i)
		}

		if d.Duration == "" {
			d.Duration = duration
			log.Debugf("item %d: missing 'duration', using default '%s'", i, duration)
		}

		if d.Scenario == "" {
			d.Scenario = reason
			log.Debugf("item %d: missing 'reason', using default '%s'", i, reason)
		}

		if d.Type == "" {
			d.Type = type_
			log.Debugf("item %d: missing 'type', using default '%s'", i, type_)
		}

		if d.Scope == "" {
			d.Scope = scope
			log.Debugf("item %d: missing 'scope', using default '%s'", i, scope)
		}

		decisions[i] = &models.Decision{
			Value:     ptr.Of(d.Value),
			Duration:  ptr.Of(d.Duration),
			Origin:    ptr.Of(types.CscliImportOrigin),
			Scenario:  ptr.Of(d.Scenario),
			Type:      ptr.Of(d.Type),
			Scope:     ptr.Of(d.Scope),
			Simulated: ptr.Of(false),
		}
	}

	if len(decisions) > 1000 {
		fmt.Fprintf(os.Stdout, "You are about to add %d decisions, this may take a while\n", len(decisions))
	}

	if batch == 0 {
		batch = len(decisions)
	} else {
		fmt.Fprintf(os.Stdout, "batch size: %d\n", batch)
	}

	allowlistedValues := make([]string, 0)

	for chunk := range slices.Chunk(decisions, batch) {
		log.Debugf("Processing chunk of %d decisions", len(chunk))

		decisionsStr := make([]string, 0, len(chunk))

		for _, d := range chunk {
			if *d.Scope != types.Ip && *d.Scope != types.Range {
				continue
			}

			decisionsStr = append(decisionsStr, *d.Value)
		}

		// Skip if no IPs or ranges
		if len(decisionsStr) == 0 {
			continue
		}

		allowlistResp, _, err := cli.client.Allowlists.CheckIfAllowlistedBulk(ctx, decisionsStr)

		if err != nil {
			return err
		}

		for _, r := range allowlistResp.Results {
			fmt.Fprintf(os.Stdout, "Value %s is allowlisted by %s\n", *r.Target, r.Allowlists)
			allowlistedValues = append(allowlistedValues, *r.Target)
		}
	}

	actualDecisions := slices.Collect(excludeAllowlistedDecisions(decisions, allowlistedValues))

	for chunk := range slices.Chunk(actualDecisions, batch) {
		importAlert := models.Alert{
			CreatedAt: time.Now().UTC().Format(time.RFC3339),
			Scenario:  ptr.Of(fmt.Sprintf("import %s: %d IPs", input, len(chunk))),

			Message: ptr.Of(""),
			Events:  []*models.Event{},
			Source: &models.Source{
				Scope: ptr.Of(""),
				Value: ptr.Of(""),
			},
			StartAt:         ptr.Of(time.Now().UTC().Format(time.RFC3339)),
			StopAt:          ptr.Of(time.Now().UTC().Format(time.RFC3339)),
			Capacity:        ptr.Of(int32(0)),
			Simulated:       ptr.Of(false),
			EventsCount:     ptr.Of(int32(len(chunk))),
			Leakspeed:       ptr.Of(""),
			ScenarioHash:    ptr.Of(""),
			ScenarioVersion: ptr.Of(""),
			Decisions:       chunk,
		}

		_, _, err = cli.client.Alerts.Add(ctx, models.AddAlertsRequest{&importAlert})
		if err != nil {
			return err
		}
	}

	fmt.Fprintf(os.Stdout, "Imported %d decisions", len(actualDecisions))

	return nil
}

func (cli *cliDecisions) newImportCmd() *cobra.Command {
	var (
		input        string
		duration     string
		scope        string
		reason       string
		decisionType string
		batch        int
		format       string
	)

	cmd := &cobra.Command{
		Use:   "import [options]",
		Short: "Import decisions from a file or pipe",
		Long: "expected format:\n" +
			"csv  : any of duration,reason,scope,type,value, with a header line\n" +
			"json :" + "`{" + `"duration": "24h", "reason": "my_scenario", "scope": "ip", "type": "ban", "value": "x.y.z.z"` + "}`",
		Args:              args.NoArgs,
		DisableAutoGenTag: true,
		Example: `decisions.csv:
duration,scope,value
24h,ip,1.2.3.4

$ cscli decisions import -i decisions.csv

decisions.json:
[{"duration": "4h", "scope": "ip", "type": "ban", "value": "1.2.3.4"}]

The file format is detected from the extension, but can be forced with the --format option
which is required when reading from standard input.

Raw values, standard input:

$ echo "1.2.3.4" | cscli decisions import -i - --format values
`,
		RunE: func(cmd *cobra.Command, args []string) error {
			return cli.import_(cmd.Context(), input, duration, scope, reason, decisionType, batch, format)
		},
	}

	flags := cmd.Flags()
	flags.SortFlags = false
	flags.StringVarP(&input, "input", "i", "", "Input file")
	flags.StringVarP(&duration, "duration", "d", "4h", "Decision duration: 1h,4h,30m")
	flags.StringVar(&scope, "scope", types.Ip, "Decision scope: ip,range,username")
	flags.StringVarP(&reason, "reason", "R", "manual", "Decision reason: <scenario-name>")
	flags.StringVarP(&decisionType, "type", "t", "ban", "Decision type: ban,captcha,throttle")
	flags.IntVar(&batch, "batch", 0, "Split import in batches of N decisions")
	flags.StringVar(&format, "format", "", "Input format: 'json', 'csv' or 'values' (each line is a value, no headers)")

	_ = cmd.MarkFlagRequired("input")

	return cmd
}