package search

import (
	"log/slog"
	"os"
	"time"

	"git.wntrmute.dev/kyle/sift/internal/config"
	"git.wntrmute.dev/kyle/sift/internal/dcache"
	"git.wntrmute.dev/kyle/sift/internal/search/dial"
)

const (
	defaultSearx = "http://127.0.0.1:8888"
	defaultBrave = "https://api.search.brave.com/res/v1/llm/context"
	defaultTav   = "https://api.tavily.com/search"
)

// Build constructs sources from config. Missing keys are listed on Engine.Degraded
// and logged once; those sources are not attempted. A source whose DNS is down
// at boot stays in the list and is retried on Search.
func Build(cfg config.Search, cache *dcache.DB, emb Embedder, log *slog.Logger) *Engine {
	timeout := config.ParseDuration(cfg.Timeout, 8*time.Second)
	ttl := config.ParseDuration(cfg.CacheTTL, time.Hour)
	k := cfg.K
	if k <= 0 {
		k = DefaultK
	}
	e := &Engine{
		Timeout:   timeout,
		DefaultK:  k,
		RerankOn:  cfg.RerankOn(),
		Cache:     cache,
		CacheTTL:  ttl,
		Embedder:  emb,
		Log:       log,
		TavilyCap: cfg.Tavily.DailyCreditCap,
	}
	if cfg.SearxNG.Enabled {
		u := cfg.SearxNG.URL
		if u == "" {
			u = defaultSearx
		}
		addPinned(e, log, NameSearxNG, u, dial.Options{Loopback: true, Timeout: timeout}, func(c *dial.Client) Source {
			return &SearxNG{Client: c}
		})
	}
	if cfg.BraveLLM.Enabled {
		key := os.Getenv("BRAVE_API_KEY")
		if key == "" {
			e.Degraded = append(e.Degraded, "search.brave_llm: missing key")
			if log != nil {
				log.Error("search source", "source", NameBraveLLM, "err", "missing key")
			}
		} else {
			u := cfg.BraveLLM.URL
			if u == "" {
				u = defaultBrave
			}
			addPinned(e, log, NameBraveLLM, u, dial.Options{Timeout: timeout}, func(c *dial.Client) Source {
				return &BraveLLM{Client: c, Key: key}
			})
		}
	}
	if cfg.Tavily.Enabled {
		key := os.Getenv("TAVILY_API_KEY")
		if key == "" {
			e.Degraded = append(e.Degraded, "search.tavily: missing key")
			if log != nil {
				log.Error("search source", "source", NameTavily, "err", "missing key")
			}
		} else {
			u := cfg.Tavily.URL
			if u == "" {
				u = defaultTav
			}
			addPinned(e, log, NameTavily, u, dial.Options{Timeout: timeout}, func(c *dial.Client) Source {
				return &Tavily{Client: c, Key: key}
			})
		}
	}
	return e
}

func addPinned(e *Engine, log *slog.Logger, name, raw string, opt dial.Options, wrap func(*dial.Client) Source) {
	c, err := dial.New(raw, opt)
	if err != nil {
		e.Degraded = append(e.Degraded, "search."+name+": unavailable")
		if log != nil {
			log.Error("search source", "source", name, "err", "unavailable")
		}
		return
	}
	e.Sources = append(e.Sources, wrap(c))
	if !c.Ready() && log != nil {
		log.Error("search source unresolved, will retry", "source", name)
	}
}