package main

import (
	"context"
	"fmt"

	"github.com/jackc/pgx/v5/pgxpool"
)

// Host represents a row from the hosts table.
type Host struct {
	ID               int64
	Hostname         string
	Protocol         string
	WarcFilename     string
	WarcRecordOffset int64
	WarcRecordLength int
}

// ProcessResult holds everything extracted from one host's WARC record.
type ProcessResult struct {
	Title         string
	IframeAllowed bool
	Icons         []Icon
	Err           error
	FetchErr      bool // true if error was during fetch (vs parse)
}

// WriteErrors tracks errors encountered during DB writes.
type WriteErrors struct {
	HostUpdate int
	IconInsert int
}

// fetchBatch gets the next batch of unparsed hosts after lastID.
func fetchBatch(ctx context.Context, pool *pgxpool.Pool, lastID int64, limit int) ([]Host, error) {
	rows, err := pool.Query(ctx,
		`SELECT id, hostname, protocol, warc_filename, warc_record_offset, warc_record_length
		 FROM hosts
		 WHERE parsed = FALSE AND id > $1
		 ORDER BY id
		 LIMIT $2`,
		lastID, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var hosts []Host
	for rows.Next() {
		var h Host
		err := rows.Scan(&h.ID, &h.Hostname, &h.Protocol, &h.WarcFilename, &h.WarcRecordOffset, &h.WarcRecordLength)
		if err != nil {
			return nil, err
		}
		hosts = append(hosts, h)
	}
	return hosts, rows.Err()
}

// writeResult writes parsed results back to the database.
// Returns counts of DB write errors encountered.
func writeResult(ctx context.Context, pool *pgxpool.Pool, host Host, result ProcessResult, logWriter *LogWriter) WriteErrors {
	var errs WriteErrors

	// Update hosts table
	_, err := pool.Exec(ctx,
		`UPDATE hosts SET html_title = $1, iframe_allowed = $2, parsed = TRUE WHERE id = $3`,
		nilIfEmpty(result.Title), result.IframeAllowed, host.ID)
	if err != nil {
		errs.HostUpdate++
		logLine := fmt.Sprintf("DB_ERROR: %s hosts_update: %v", host.Hostname, err)
		fmt.Println(logLine)
		if logWriter != nil {
			logWriter.Write(logLine, true)
		}
		return errs
	}

	// Insert /favicon.ico entry
	faviconURL := fmt.Sprintf("%s://%s/favicon.ico", host.Protocol, host.Hostname)
	_, err = pool.Exec(ctx,
		`INSERT INTO icons (host_id, url, source) VALUES ($1, $2, 'favicon_ico')`,
		host.ID, faviconURL)
	if err != nil {
		errs.IconInsert++
		logLine := fmt.Sprintf("DB_ERROR: %s icon_insert: %v", host.Hostname, err)
		fmt.Println(logLine)
		if logWriter != nil {
			logWriter.Write(logLine, true)
		}
	}

	// Insert link rel="icon" entries
	for _, icon := range result.Icons {
		_, err = pool.Exec(ctx,
			`INSERT INTO icons (host_id, url, source, rel_type, rel_sizes) VALUES ($1, $2, $3, $4, $5)`,
			host.ID, icon.URL, icon.Source, nilIfEmpty(icon.RelType), nilIfEmpty(icon.RelSizes))
		if err != nil {
			errs.IconInsert++
			logLine := fmt.Sprintf("DB_ERROR: %s icon_insert: %v", host.Hostname, err)
			fmt.Println(logLine)
			if logWriter != nil {
				logWriter.Write(logLine, true)
			}
		}
	}

	return errs
}

func nilIfEmpty(s string) *string {
	if s == "" {
		return nil
	}
	return &s
}