package api

import (
	"net/http"
	"path/filepath"

	"github.com/will/k8s-agent-dashboard/internal/claude"
)

// ClaudeLoader is a minimal interface for Claude Ops endpoints.
//
// Keep it small so handlers are easy to test with fakes.
type ClaudeLoader interface {
	ClaudeDir() string
	LoadStatsCache() (*claude.StatsCache, error)
	ListDir(name string) ([]claude.DirEntry, error)
	FileMeta(relPath string) (claude.FileMeta, error)
	PathExists(relPath string) bool
}

func GetClaudeStats(loader ClaudeLoader) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		stats, err := loader.LoadStatsCache()
		if err != nil {
			respondError(w, http.StatusInternalServerError, err.Error())
			return
		}
		respondJSON(w, http.StatusOK, stats)
	}
}

type ClaudeSummaryResponse struct {
	Totals   ClaudeSummaryTotals          `json:"totals"`
	PerModel map[string]claude.ModelUsage `json:"perModel"`
	Derived  ClaudeSummaryDerived         `json:"derived"`
}

type ClaudeSummaryTotals struct {
	TotalSessions int `json:"totalSessions"`
	TotalMessages int `json:"totalMessages"`
}

type ClaudeSummaryDerived struct {
	CacheHitRatioEstimate  float64 `json:"cacheHitRatioEstimate"`
	TopModelByOutputTokens string  `json:"topModelByOutputTokens"`
}

func GetClaudeSummary(loader ClaudeLoader) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		stats, err := loader.LoadStatsCache()
		if err != nil {
			respondError(w, http.StatusInternalServerError, err.Error())
			return
		}

		resp := ClaudeSummaryResponse{
			Totals: ClaudeSummaryTotals{
				TotalSessions: stats.TotalSessions,
				TotalMessages: stats.TotalMessages,
			},
			PerModel: stats.ModelUsage,
		}

		var inputTokens, cacheRead, cacheCreate int
		maxOut := -1
		topModel := ""
		for model, usage := range stats.ModelUsage {
			inputTokens += usage.InputTokens
			cacheRead += usage.CacheReadInputTokens
			cacheCreate += usage.CacheCreationInputTokens
			if usage.OutputTokens > maxOut {
				maxOut = usage.OutputTokens
				topModel = model
			}
		}

		den := float64(inputTokens + cacheRead + cacheCreate)
		ratio := 0.0
		if den > 0 {
			ratio = float64(cacheRead) / den
		}

		resp.Derived = ClaudeSummaryDerived{
			CacheHitRatioEstimate:  ratio,
			TopModelByOutputTokens: topModel,
		}

		respondJSON(w, http.StatusOK, resp)
	}
}

func GetClaudeHealth(loader ClaudeLoader) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		checks := map[string]bool{}
		missing := false
		for _, rel := range []string{"stats-cache.json", "history.jsonl", filepath.Join("state", "component-registry.json")} {
			exists := loader.PathExists(rel)
			checks[rel] = exists
			if !exists {
				missing = true
			}
		}

		status := "ok"
		if missing {
			status = "degraded"
		}

		respondJSON(w, http.StatusOK, map[string]any{
			"status":     status,
			"claudeDir":  loader.ClaudeDir(),
			"fileChecks": checks,
		})
	}
}

func GetClaudeInventory(loader ClaudeLoader) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		agents, err := loader.ListDir("agents")
		if err != nil {
			respondError(w, http.StatusInternalServerError, err.Error())
			return
		}
		skills, err := loader.ListDir("skills")
		if err != nil {
			respondError(w, http.StatusInternalServerError, err.Error())
			return
		}
		commands, err := loader.ListDir("commands")
		if err != nil {
			respondError(w, http.StatusInternalServerError, err.Error())
			return
		}

		respondJSON(w, http.StatusOK, map[string]any{
			"agents":   agents,
			"skills":   skills,
			"commands": commands,
		})
	}
}

func GetClaudeDebugFiles(loader ClaudeLoader) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		var metas []claude.FileMeta
		for _, rel := range []string{
			"stats-cache.json",
			"history.jsonl",
			filepath.Join("state", "component-registry.json"),
		} {
			meta, err := loader.FileMeta(rel)
			if err != nil {
				respondError(w, http.StatusInternalServerError, err.Error())
				return
			}
			metas = append(metas, meta)
		}
		respondJSON(w, http.StatusOK, map[string]any{
			"files": metas,
		})
	}
}