package databrickscfg

import (
	"context"
	"errors"
	"fmt"
	"os"
	"strings"

	"github.com/databricks/cli/libs/log"
	"github.com/databricks/databricks-sdk-go/config"
	"gopkg.in/ini.v1"
)

var ResolveProfileFromHost = profileFromHostLoader{}

var errNoMatchingProfiles = errors.New("no matching config profiles found")

type errMultipleProfiles []string

func (e errMultipleProfiles) Error() string {
	return fmt.Sprintf("multiple profiles matched: %s", strings.Join(e, ", "))
}

func findMatchingProfile(configFile *config.File, matcher func(*ini.Section) bool) (*ini.Section, error) {
	// Look for sections in the configuration file that match the configured host.
	var matching []*ini.Section
	for _, section := range configFile.Sections() {
		if !matcher(section) {
			continue
		}
		matching = append(matching, section)
	}

	// If there are no matching sections, we don't do anything.
	if len(matching) == 0 {
		return nil, errNoMatchingProfiles
	}

	// If there are multiple matching sections, let the user know it is impossible
	// to unambiguously select a profile to use.
	if len(matching) > 1 {
		var names errMultipleProfiles
		for _, section := range matching {
			names = append(names, section.Name())
		}

		return nil, names
	}

	return matching[0], nil
}

type profileFromHostLoader struct{}

func (l profileFromHostLoader) Name() string {
	return "resolve-profile-from-host"
}

func (l profileFromHostLoader) Configure(cfg *config.Config) error {
	// Skip an attempt to resolve a profile from the host if any authentication
	// is already configured (either directly, through environment variables, or
	// if a profile was specified).
	if cfg.Host == "" || l.isAnyAuthConfigured(cfg) {
		return nil
	}

	ctx := context.Background()
	configFile, err := config.LoadFile(cfg.ConfigFile)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return fmt.Errorf("cannot parse config file: %w", err)
	}
	// Normalized version of the configured host.
	host := normalizeHost(cfg.Host)
	match, err := findMatchingProfile(configFile, func(s *ini.Section) bool {
		key, err := s.GetKey("host")
		if err != nil {
			log.Tracef(ctx, "section %s: %s", s.Name(), err)
			return false
		}

		// Check if this section matches the normalized host
		return normalizeHost(key.Value()) == host
	})
	if err == errNoMatchingProfiles {
		return nil
	}
	if err, ok := err.(errMultipleProfiles); ok {
		return fmt.Errorf(
			"%s: %w: please set DATABRICKS_CONFIG_PROFILE to specify one",
			host, err)
	}
	if err != nil {
		return err
	}

	log.Debugf(ctx, "Loading profile %s because of host match", match.Name())
	err = config.ConfigAttributes.ResolveFromStringMap(cfg, match.KeysHash())
	if err != nil {
		return fmt.Errorf("%s %s profile: %w", configFile.Path(), match.Name(), err)
	}

	return nil
}

func (l profileFromHostLoader) isAnyAuthConfigured(cfg *config.Config) bool {
	for _, a := range config.ConfigAttributes {
		if a.Auth == "" {
			continue
		}
		if !a.IsZero(cfg) {
			return true
		}
	}
	return false
}