package sourcemaps

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"sync"

	sm "github.com/go-sourcemap/sourcemap"
)

var frameRE = regexp.MustCompile(`(.*?)(https?://[^ )]+|[^ )]+):(\d+):(\d+)(\)?\s*)$`)

type Resolver struct {
	dir  string
	mu   sync.RWMutex
	maps map[string]*sm.Consumer
}

func New(dir string) (*Resolver, error) {
	if dir == "" {
		dir = "./sourcemaps"
	}
	if err := os.MkdirAll(dir, 0750); err != nil {
		return nil, err
	}
	return &Resolver{dir: dir, maps: make(map[string]*sm.Consumer)}, nil
}

func key(release, source string) string { return release + "\x00" + normalize(source) }

func normalize(source string) string {
	source = strings.Split(source, "?")[0]
	if i := strings.Index(source, "/assets/"); i >= 0 {
		return source[i:]
	}
	return strings.TrimPrefix(source, "./")
}

func (r *Resolver) Upload(release, source string, body io.Reader) error {
	if strings.TrimSpace(release) == "" || strings.TrimSpace(source) == "" {
		return fmt.Errorf("release and source are required")
	}
	b, err := io.ReadAll(io.LimitReader(body, 50<<20))
	if err != nil {
		return err
	}
	consumer, err := sm.Parse(source+".map", b)
	if err != nil {
		return fmt.Errorf("invalid source map: %w", err)
	}
	name := filepath.Join(r.dir, safe(release)+"-"+safe(normalize(source))+".map")
	if err := os.WriteFile(name, b, 0600); err != nil {
		return err
	}
	r.mu.Lock()
	r.maps[key(release, source)] = consumer
	r.mu.Unlock()
	return nil
}

func safe(s string) string {
	s = strings.ReplaceAll(s, "/", "_")
	s = strings.ReplaceAll(s, "\\", "_")
	return strings.Map(func(r rune) rune {
		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || strings.ContainsRune("._-", r) {
			return r
		}
		return '_'
	}, s)
}

func (r *Resolver) ResolveStack(release, stack string) string {
	if release == "" || stack == "" {
		return stack
	}
	r.mu.RLock()
	defer r.mu.RUnlock()
	lines := strings.Split(stack, "\n")
	for i, line := range lines {
		m := frameRE.FindStringSubmatch(line)
		if m == nil {
			continue
		}
		genLine, _ := strconv.Atoi(m[3])
		genCol, _ := strconv.Atoi(m[4])
		consumer := r.maps[key(release, m[2])]
		if consumer == nil {
			continue
		}
		source, name, srcLine, srcCol, ok := consumer.Source(genLine, genCol)
		if !ok {
			continue
		}
		label := source
		if name != "" {
			label += " (" + name + ")"
		}
		lines[i] = fmt.Sprintf("%s%s:%d:%d%s  [mapped from %s:%d:%d]", m[1], label, srcLine, srcCol, m[5], m[2], genLine, genCol)
	}
	return strings.Join(lines, "\n")
}