package storage

import (
	"context"
	"database/sql"
	"encoding/json"
	"regexp"
	"strings"
	"time"

	"github.com/araddon/dateparse"
	"github.com/axllent/mailpit/internal/logger"
	"github.com/axllent/mailpit/internal/tools"
	"github.com/leporo/sqlf"
)

// Search will search a mailbox for search terms.
// The search is broken up by segments (exact phrases can be quoted), and interprets specific terms such as:
// is:read, is:unread, has:attachment, to:<term>, from:<term> & subject:<term>
// Negative searches also also included by prefixing the search term with a `-` or `!`
func Search(search, timezone string, start, limit int) ([]MessageSummary, int, error) {
	results := []MessageSummary{}
	allResults := []MessageSummary{}
	tsStart := time.Now()
	nrResults := 0
	if limit < 0 {
		limit = 50
	}

	q := searchQueryBuilder(search, timezone)
	var err error

	if err := q.QueryAndClose(context.TODO(), db, func(row *sql.Rows) {
		var created float64
		var id string
		var messageID string
		var subject string
		var metadata string
		var size float64
		var attachments int
		var snippet string
		var read int
		var ignore string
		em := MessageSummary{}

		if err := row.Scan(&created, &id, &messageID, &subject, &metadata, &size, &attachments, &read, &snippet, &ignore, &ignore, &ignore, &ignore, &ignore); err != nil {
			logger.Log().Errorf("[db] %s", err.Error())
			return
		}

		if err := json.Unmarshal([]byte(metadata), &em); err != nil {
			logger.Log().Errorf("[db] %s", err.Error())
			return
		}

		em.Created = time.UnixMilli(int64(created))
		em.ID = id
		em.MessageID = messageID
		em.Subject = subject
		em.Size = size
		em.Attachments = attachments
		em.Read = read == 1
		em.Snippet = snippet

		allResults = append(allResults, em)
	}); err != nil {
		return results, nrResults, err
	}

	dbLastAction = time.Now()

	nrResults = len(allResults)

	if nrResults > start {
		end := nrResults
		if nrResults >= start+limit {
			end = start + limit
		}

		results = allResults[start:end]
	}

	// set tags for listed messages only
	for i, m := range results {
		results[i].Tags = getMessageTags(m.ID)
	}

	elapsed := time.Since(tsStart)

	logger.Log().Debugf("[db] search for \"%s\" in %s", search, elapsed)

	return results, nrResults, err
}

// DeleteSearch will delete all messages for search terms.
// The search is broken up by segments (exact phrases can be quoted), and interprets specific terms such as:
// is:read, is:unread, has:attachment, to:<term>, from:<term> & subject:<term>
// Negative searches also also included by prefixing the search term with a `-` or `!`
func DeleteSearch(search, timezone string) error {
	q := searchQueryBuilder(search, timezone)

	ids := []string{}
	deleteSize := float64(0)

	if err := q.QueryAndClose(context.TODO(), db, func(row *sql.Rows) {
		var created float64
		var id string
		var messageID string
		var subject string
		var metadata string
		var size float64
		var attachments int
		var read int
		var snippet string
		var ignore string

		if err := row.Scan(&created, &id, &messageID, &subject, &metadata, &size, &attachments, &read, &snippet, &ignore, &ignore, &ignore, &ignore, &ignore); err != nil {
			logger.Log().Errorf("[db] %s", err.Error())
			return
		}

		ids = append(ids, id)
		deleteSize = deleteSize + size
	}); err != nil {
		return err
	}

	if len(ids) > 0 {
		total := len(ids)

		// split ids into chunks of 1000 ids
		var chunks [][]string
		if total > 1000 {
			chunkSize := 1000
			chunks = make([][]string, 0, (len(ids)+chunkSize-1)/chunkSize)
			for chunkSize < len(ids) {
				ids, chunks = ids[chunkSize:], append(chunks, ids[0:chunkSize:chunkSize])
			}
			if len(ids) > 0 {
				// add remaining ids <= 1000
				chunks = append(chunks, ids)
			}
		} else {
			chunks = append(chunks, ids)
		}

		// begin a transaction to ensure both the message
		// and data are deleted successfully
		tx, err := db.BeginTx(context.Background(), nil)
		if err != nil {
			return err
		}

		// roll back if it fails
		defer tx.Rollback()

		for _, ids := range chunks {
			delIDs := make([]interface{}, len(ids))
			for i, id := range ids {
				delIDs[i] = id
			}

			sqlDelete1 := `DELETE FROM ` + tenant("mailbox") + ` WHERE ID IN (?` + strings.Repeat(",?", len(ids)-1) + `)` // #nosec

			_, err = tx.Exec(sqlDelete1, delIDs...)
			if err != nil {
				return err
			}

			sqlDelete2 := `DELETE FROM ` + tenant("mailbox_data") + ` WHERE ID IN (?` + strings.Repeat(",?", len(ids)-1) + `)` // #nosec

			_, err = tx.Exec(sqlDelete2, delIDs...)
			if err != nil {
				return err
			}

			sqlDelete3 := `DELETE FROM ` + tenant("message_tags") + ` WHERE ID IN (?` + strings.Repeat(",?", len(ids)-1) + `)` // #nosec

			_, err = tx.Exec(sqlDelete3, delIDs...)
			if err != nil {
				return err
			}
		}

		err = tx.Commit()

		if err := pruneUnusedTags(); err != nil {
			return err
		}

		if err == nil {
			logger.Log().Debugf("[db] deleted %d messages matching %s", total, search)
		}

		dbLastAction = time.Now()
		addDeletedSize(int64(deleteSize))

		logMessagesDeleted(total)

		BroadcastMailboxStats()
	}

	return nil
}

// SearchParser returns the SQL syntax for the database search based on the search arguments
func searchQueryBuilder(searchString, timezone string) *sqlf.Stmt {
	// group strings with quotes as a single argument and remove quotes
	args := tools.ArgsParser(searchString)

	if timezone != "" {
		loc, err := time.LoadLocation(timezone)
		if err != nil {
			logger.Log().Warnf("ignoring invalid timezone:\"%s\"", timezone)
		} else {
			time.Local = loc
		}
	}

	q := sqlf.From(tenant("mailbox") + " m").
		Select(`m.Created, m.ID, m.MessageID, m.Subject, m.Metadata, m.Size, m.Attachments, m.Read,
			m.Snippet,
			IFNULL(json_extract(Metadata, '$.To'), '{}') as ToJSON,
			IFNULL(json_extract(Metadata, '$.From'), '{}') as FromJSON,
			IFNULL(json_extract(Metadata, '$.Cc'), '{}') as CcJSON,
			IFNULL(json_extract(Metadata, '$.Bcc'), '{}') as BccJSON,
			IFNULL(json_extract(Metadata, '$.ReplyTo'), '{}') as ReplyToJSON
		`).
		OrderBy("m.Created DESC")

	for _, w := range args {
		if cleanString(w) == "" {
			continue
		}

		// lowercase search to try match search prefixes
		lw := strings.ToLower(w)

		exclude := false
		// search terms starting with a `-` or `!` imply an exclude
		if len(w) > 1 && (strings.HasPrefix(w, "-") || strings.HasPrefix(w, "!")) {
			exclude = true
			w = w[1:]
			lw = lw[1:]
		}

		re := regexp.MustCompile(`[a-zA-Z0-9]+`)
		if !re.MatchString(w) {
			continue
		}

		if strings.HasPrefix(lw, "to:") {
			w = cleanString(w[3:])
			if w != "" {
				if exclude {
					q.Where("ToJSON NOT LIKE ?", "%"+escPercentChar(w)+"%")
				} else {
					q.Where("ToJSON LIKE ?", "%"+escPercentChar(w)+"%")
				}
			}
		} else if strings.HasPrefix(lw, "from:") {
			w = cleanString(w[5:])
			if w != "" {
				if exclude {
					q.Where("FromJSON NOT LIKE ?", "%"+escPercentChar(w)+"%")
				} else {
					q.Where("FromJSON LIKE ?", "%"+escPercentChar(w)+"%")
				}
			}
		} else if strings.HasPrefix(lw, "cc:") {
			w = cleanString(w[3:])
			if w != "" {
				if exclude {
					q.Where("CcJSON NOT LIKE ?", "%"+escPercentChar(w)+"%")
				} else {
					q.Where("CcJSON LIKE ?", "%"+escPercentChar(w)+"%")
				}
			}
		} else if strings.HasPrefix(lw, "bcc:") {
			w = cleanString(w[4:])
			if w != "" {
				if exclude {
					q.Where("BccJSON NOT LIKE ?", "%"+escPercentChar(w)+"%")
				} else {
					q.Where("BccJSON LIKE ?", "%"+escPercentChar(w)+"%")
				}
			}
		} else if strings.HasPrefix(lw, "reply-to:") {
			w = cleanString(w[9:])
			if w != "" {
				if exclude {
					q.Where("ReplyToJSON NOT LIKE ?", "%"+escPercentChar(w)+"%")
				} else {
					q.Where("ReplyToJSON LIKE ?", "%"+escPercentChar(w)+"%")
				}
			}
		} else if strings.HasPrefix(lw, "subject:") {
			w = w[8:]
			if w != "" {
				if exclude {
					q.Where("Subject NOT LIKE ?", "%"+escPercentChar(w)+"%")
				} else {
					q.Where("Subject LIKE ?", "%"+escPercentChar(w)+"%")
				}
			}
		} else if strings.HasPrefix(lw, "message-id:") {
			w = cleanString(w[11:])
			if w != "" {
				if exclude {
					q.Where("MessageID NOT LIKE ?", "%"+escPercentChar(w)+"%")
				} else {
					q.Where("MessageID LIKE ?", "%"+escPercentChar(w)+"%")
				}
			}
		} else if strings.HasPrefix(lw, "tag:") {
			w = cleanString(w[4:])
			if w != "" {
				if exclude {
					q.Where(`m.ID NOT IN (SELECT mt.ID FROM `+tenant("message_tags")+` mt JOIN `+tenant("tags")+` t ON mt.TagID = t.ID WHERE t.Name = ?)`, w)
				} else {
					q.Where(`m.ID IN (SELECT mt.ID FROM `+tenant("message_tags")+` mt JOIN `+tenant("tags")+` t ON mt.TagID = t.ID WHERE t.Name = ?)`, w)
				}
			}
		} else if lw == "is:read" {
			if exclude {
				q.Where("Read = 0")
			} else {
				q.Where("Read = 1")
			}
		} else if lw == "is:unread" {
			if exclude {
				q.Where("Read = 1")
			} else {
				q.Where("Read = 0")
			}
		} else if lw == "is:tagged" {
			if exclude {
				q.Where(`m.ID NOT IN (SELECT DISTINCT mt.ID FROM ` + tenant("message_tags") + ` mt JOIN tags t ON mt.TagID = t.ID)`)
			} else {
				q.Where(`m.ID IN (SELECT DISTINCT mt.ID FROM ` + tenant("message_tags") + ` mt JOIN tags t ON mt.TagID = t.ID)`)
			}
		} else if lw == "has:attachment" || lw == "has:attachments" {
			if exclude {
				q.Where("Attachments = 0")
			} else {
				q.Where("Attachments > 0")
			}
		} else if strings.HasPrefix(lw, "after:") {
			w = cleanString(w[6:])
			if w != "" {
				t, err := dateparse.ParseLocal(w)
				if err != nil {
					logger.Log().Warnf("ignoring invalid after: date \"%s\"", w)
				} else {
					timestamp := t.UnixMilli()
					if exclude {
						q.Where(`m.Created <= ?`, timestamp)
					} else {
						q.Where(`m.Created >= ?`, timestamp)
					}
				}
			}
		} else if strings.HasPrefix(lw, "before:") {
			w = cleanString(w[7:])
			if w != "" {
				t, err := dateparse.ParseLocal(w)
				if err != nil {
					logger.Log().Warnf("ignoring invalid before: date \"%s\"", w)
				} else {
					timestamp := t.UnixMilli()
					if exclude {
						q.Where(`m.Created >= ?`, timestamp)
					} else {
						q.Where(`m.Created <= ?`, timestamp)
					}
				}
			}
		} else {
			// search text
			if exclude {
				q.Where("SearchText NOT LIKE ?", "%"+cleanString(escPercentChar(strings.ToLower(w)))+"%")
			} else {
				q.Where("SearchText LIKE ?", "%"+cleanString(escPercentChar(strings.ToLower(w)))+"%")
			}
		}
	}

	return q
}