package archtest

import (
	"fmt"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"time"

	"gopkg.in/yaml.v3"
)

const (
	KindImport   = "import"
	KindSQLWrite = "sql_write"
	KindPath     = "path"
	KindEvent    = "event"
)

type Boundaries struct {
	Imports         map[string][]string `yaml:"imports"`
	TableOwners     map[string][]string `yaml:"table_owners"`
	PathOwners      map[string][]string `yaml:"path_owners"`
	EventProducers  map[string][]string `yaml:"event_producers"`
	EventConsumers  map[string][]string `yaml:"event_consumers"`
	UnwrapOwners    []string            `yaml:"unwrap_owners"`
	Exceptions      []Exception         `yaml:"exceptions"`
	BaselineCounts  map[string]int      `yaml:"baseline_counts"`
	BlockKinds      []string            `yaml:"block_kinds"`
}

type Exception struct {
	Kind      string `yaml:"kind"`
	Package   string `yaml:"package"`
	File      string `yaml:"file"`
	Symbol    string `yaml:"symbol"`
	Owner     string `yaml:"owner"`
	Reason    string `yaml:"reason"`
	Milestone string `yaml:"milestone"`
	Expires   string `yaml:"expires"`
}

type Finding struct {
	Kind    string
	Package string
	File    string
	Symbol  string
	Detail  string
}

func (f Finding) Key() string {
	return f.Kind + "|" + f.Package + "|" + filepath.ToSlash(f.File) + "|" + f.Symbol
}

func ModuleRoot() (string, error) {
	_, file, _, ok := runtime.Caller(0)
	if !ok {
		return "", fmt.Errorf("archtest: cannot locate caller")
	}
	dir := filepath.Dir(file)
	for {
		if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
			return dir, nil
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			return "", fmt.Errorf("archtest: go.mod not found")
		}
		dir = parent
	}
}

func LoadBoundaries(path string) (*Boundaries, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	var out Boundaries
	if err := yaml.Unmarshal(b, &out); err != nil {
		return nil, err
	}
	if out.Imports == nil {
		out.Imports = map[string][]string{}
	}
	if out.TableOwners == nil {
		out.TableOwners = map[string][]string{}
	}
	if out.PathOwners == nil {
		out.PathOwners = map[string][]string{}
	}
	if out.EventProducers == nil {
		out.EventProducers = map[string][]string{}
	}
	if out.EventConsumers == nil {
		out.EventConsumers = map[string][]string{}
	}
	if out.UnwrapOwners == nil {
		out.UnwrapOwners = []string{}
	}
	if out.BaselineCounts == nil {
		out.BaselineCounts = map[string]int{}
	}
	return &out, nil
}

func DefaultBoundariesPath(root string) string {
	return filepath.Join(root, ".doc", "system-design", "module-boundaries.yaml")
}

func allowedHas(list []string, needle string) bool {
	for _, p := range list {
		if strings.TrimSpace(p) == needle {
			return true
		}
	}
	return false
}

func (e Exception) validate(now time.Time) error {
	if strings.TrimSpace(e.Owner) == "" {
		return fmt.Errorf("missing owner")
	}
	if strings.TrimSpace(e.Reason) == "" {
		return fmt.Errorf("missing reason")
	}
	if strings.TrimSpace(e.Milestone) == "" {
		return fmt.Errorf("missing milestone")
	}
	if strings.TrimSpace(e.Expires) == "" {
		return fmt.Errorf("missing expires")
	}
	day, err := time.ParseInLocation("2006-01-02", e.Expires, time.UTC)
	if err != nil {
		return fmt.Errorf("invalid expires %q", e.Expires)
	}
	// expires is inclusive through that calendar day (UTC).
	if !now.UTC().Before(day.Add(24 * time.Hour)) {
		return fmt.Errorf("expired on %s", e.Expires)
	}
	return nil
}

func (e Exception) matches(f Finding) bool {
	if e.Kind != f.Kind {
		return false
	}
	if e.Package != "" && e.Package != f.Package {
		return false
	}
	if e.File != "" && filepath.ToSlash(e.File) != filepath.ToSlash(f.File) {
		return false
	}
	if e.Symbol != "" && e.Symbol != f.Symbol {
		return false
	}
	return true
}