package opensuse

import (
	"context"
	"fmt"
	"strings"
	"sync"
	"time"

	"tangled.org/odd.computer/isomorph/internal/fetch"
)

// giturls.good on rb.zq1.de is the output of Bernhard Wiedemann's findvcs script over every
// Factory spec: "<pkg>/<spec>.spec = <git url>" per line. It was derived from the same spec
// URL/Source fields we parse (and parts of it date from 2022), so it corroborates rather than
// proves an upstream. Loaded once per process per base URL; failures are non-fatal.
var giturlsCache = struct {
	mu sync.Mutex
	m  map[string]*giturlsEntry
}{m: map[string]*giturlsEntry{}}

type giturlsEntry struct {
	once sync.Once
	urls map[string][]string
	err  error
}

// ParseGitURLs parses the giturls(.good) format into package -> URLs. Lines with "= unknown",
// "debug:" lines and findvcs "FIXME" placeholders are skipped.
func ParseGitURLs(text string) map[string][]string {
	out := map[string][]string{}
	for _, line := range strings.Split(text, "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "debug:") || strings.HasPrefix(line, "#") {
			continue
		}
		key, val, ok := strings.Cut(line, " = ")
		if !ok {
			continue
		}
		val = strings.TrimSpace(val)
		if val == "" || val == "unknown" || strings.Contains(val, "FIXME") || strings.ContainsAny(val, " \t") {
			continue
		}
		pkg := strings.TrimSpace(key)
		if i := strings.Index(pkg, "/"); i >= 0 {
			pkg = pkg[:i]
		}
		if pkg == "" {
			continue
		}
		out[pkg] = appendUnique(out[pkg], val)
	}
	return out
}

// loadGitURLs fetches and parses giturls.good (7-day TTL) once per process.
func (r *Resolver) loadGitURLs(ctx context.Context) (map[string][]string, error) {
	giturlsCache.mu.Lock()
	e, ok := giturlsCache.m[r.ZQ1Base]
	if !ok {
		e = &giturlsEntry{}
		giturlsCache.m[r.ZQ1Base] = e
	}
	giturlsCache.mu.Unlock()
	e.once.Do(func() {
		u := strings.TrimSuffix(r.ZQ1Base, "/") + "/giturls.good"
		b, err := r.c.Get(ctx, u, fetch.WithTTL(7*24*time.Hour))
		if err != nil {
			e.err = fmt.Errorf("giturls: %w", err)
			return
		}
		e.urls = ParseGitURLs(string(b))
	})
	return e.urls, e.err
}

func appendUnique(s []string, v string) []string {
	if v == "" {
		return s
	}
	for _, x := range s {
		if x == v {
			return s
		}
	}
	return append(s, v)
}