package api

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"net/http"
	"os/exec"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/thepeterstone/claudomator/internal/deployment"
	"github.com/thepeterstone/claudomator/internal/task"
)

// createStoryBranch creates a new git branch in localPath from origin/main
// and pushes it to origin. Idempotent: treats "already exists" as success.
func createStoryBranch(localPath, branchName string) error {
	// Fetch latest from origin so origin/main is up to date.
	if out, err := exec.Command("git", "-C", localPath, "fetch", "origin").CombinedOutput(); err != nil {
		return fmt.Errorf("git fetch: %w (output: %s)", err, string(out))
	}
	base := "origin/main"
	out, err := exec.Command("git", "-C", localPath, "checkout", "-b", branchName, base).CombinedOutput()
	if err != nil {
		if !strings.Contains(string(out), "already exists") {
			return fmt.Errorf("git checkout -b: %w (output: %s)", err, string(out))
		}
		// Branch exists; switch to it — idempotent.
		if out2, err2 := exec.Command("git", "-C", localPath, "checkout", branchName).CombinedOutput(); err2 != nil {
			return fmt.Errorf("git checkout: %w (output: %s)", err2, string(out2))
		}
	}
	if out, err := exec.Command("git", "-C", localPath, "push", "origin", branchName).CombinedOutput(); err != nil {
		return fmt.Errorf("git push: %w (output: %s)", err, string(out))
	}
	return nil
}

func (s *Server) handleListStories(w http.ResponseWriter, r *http.Request) {
	stories, err := s.store.ListStories()
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	if stories == nil {
		stories = []*task.Story{}
	}
	writeJSON(w, http.StatusOK, stories)
}

func (s *Server) handleCreateStory(w http.ResponseWriter, r *http.Request) {
	var st task.Story
	if err := json.NewDecoder(r.Body).Decode(&st); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON: " + err.Error()})
		return
	}
	if st.Name == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "name is required"})
		return
	}
	if st.ID == "" {
		st.ID = uuid.New().String()
	}
	if st.Status == "" {
		st.Status = task.StoryPending
	}
	if err := s.store.CreateStory(&st); err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	writeJSON(w, http.StatusCreated, st)
}

func (s *Server) handleGetStory(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	st, err := s.store.GetStory(id)
	if err != nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "story not found"})
		return
	}
	writeJSON(w, http.StatusOK, st)
}

func (s *Server) handleListStoryTasks(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	if _, err := s.store.GetStory(id); err != nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "story not found"})
		return
	}
	tasks, err := s.store.ListTasksByStory(id)
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	if tasks == nil {
		tasks = []*task.Task{}
	}
	writeJSON(w, http.StatusOK, tasks)
}

func (s *Server) handleAddTaskToStory(w http.ResponseWriter, r *http.Request) {
	storyID := r.PathValue("id")
	st, err := s.store.GetStory(storyID)
	if err != nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "story not found"})
		return
	}
	_ = st

	var input struct {
		Name          string           `json:"name"`
		Description   string           `json:"description"`
		Project       string           `json:"project"`
		RepositoryURL string           `json:"repository_url"`
		Agent         task.AgentConfig `json:"agent"`
		Claude        task.AgentConfig `json:"claude"`
		Timeout       string           `json:"timeout"`
		Priority      string           `json:"priority"`
		Tags          []string         `json:"tags"`
		ParentTaskID  string           `json:"parent_task_id"`
	}
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON: " + err.Error()})
		return
	}
	if input.Agent.Instructions == "" && input.Claude.Instructions != "" {
		input.Agent = input.Claude
	}

	existing, err := s.store.ListTasksByStory(storyID)
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}

	now := time.Now().UTC()
	t := &task.Task{
		ID:            uuid.New().String(),
		Name:          input.Name,
		Description:   input.Description,
		Project:       input.Project,
		RepositoryURL: input.RepositoryURL,
		Agent:         input.Agent,
		Priority:      task.Priority(input.Priority),
		Tags:          input.Tags,
		DependsOn:     []string{},
		Retry:         task.RetryConfig{MaxAttempts: 1, Backoff: "exponential"},
		State:         task.StatePending,
		StoryID:       storyID,
		ParentTaskID:  input.ParentTaskID,
		CreatedAt:     now,
		UpdatedAt:     now,
	}

	if t.Agent.Type == "" {
		t.Agent.Type = "claude"
	}
	if t.Priority == "" {
		t.Priority = task.PriorityNormal
	}
	if t.Tags == nil {
		t.Tags = []string{}
	}
	if input.Timeout != "" {
		dur, err := time.ParseDuration(input.Timeout)
		if err != nil {
			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid timeout: " + err.Error()})
			return
		}
		t.Timeout.Duration = dur
	}

	// Auto-wire depends_on: new task depends on the last existing task (sorted ASC by created_at).
	if len(existing) > 0 {
		lastTask := existing[len(existing)-1]
		t.DependsOn = []string{lastTask.ID}
	}

	if err := s.store.CreateTask(t); err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	writeJSON(w, http.StatusCreated, t)
}

func (s *Server) handleUpdateStoryStatus(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")
	st, err := s.store.GetStory(id)
	if err != nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "story not found"})
		return
	}

	var input struct {
		Status task.StoryState `json:"status"`
	}
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON: " + err.Error()})
		return
	}
	if !task.ValidStoryTransition(st.Status, input.Status) {
		writeJSON(w, http.StatusConflict, map[string]string{
			"error": "invalid story status transition from " + string(st.Status) + " to " + string(input.Status),
		})
		return
	}
	if err := s.store.UpdateStoryStatus(id, input.Status); err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}
	writeJSON(w, http.StatusOK, map[string]string{"message": "story status updated", "story_id": id, "status": string(input.Status)})
}

func (s *Server) handleApproveStory(w http.ResponseWriter, r *http.Request) {
	var input struct {
		Name       string                    `json:"name"`
		BranchName string                    `json:"branch_name"`
		ProjectID  string                    `json:"project_id"`
		Tasks      []elaboratedStoryTask     `json:"tasks"`
		Validation elaboratedStoryValidation `json:"validation"`
	}
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid JSON: " + err.Error()})
		return
	}
	if input.Name == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "name is required"})
		return
	}

	validationJSON, _ := json.Marshal(input.Validation)
	now := time.Now().UTC()
	story := &task.Story{
		ID:             uuid.New().String(),
		Name:           input.Name,
		ProjectID:      input.ProjectID,
		BranchName:     input.BranchName,
		ValidationJSON: string(validationJSON),
		Status:         task.StoryPending,
		CreatedAt:      now,
		UpdatedAt:      now,
	}
	if err := s.store.CreateStory(story); err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}

	taskIDs := make([]string, 0, len(input.Tasks))
	var prevTaskID string
	for _, tp := range input.Tasks {
		t := &task.Task{
			ID:        uuid.New().String(),
			Name:      tp.Name,
			Project:   input.ProjectID,
			StoryID:   story.ID,
			Agent:     task.AgentConfig{Type: "claude", Instructions: tp.Instructions},
			Priority:  task.PriorityNormal,
			Tags:      []string{},
			DependsOn: []string{},
			Retry:     task.RetryConfig{MaxAttempts: 1, Backoff: "exponential"},
			State:     task.StatePending,
			CreatedAt: time.Now().UTC(),
			UpdatedAt: time.Now().UTC(),
		}
		if prevTaskID != "" {
			t.DependsOn = []string{prevTaskID}
		}
		if err := s.store.CreateTask(t); err != nil {
			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
			return
		}
		taskIDs = append(taskIDs, t.ID)

		var prevSubtaskID string
		for _, sub := range tp.Subtasks {
			st := &task.Task{
				ID:           uuid.New().String(),
				Name:         sub.Name,
				Project:      input.ProjectID,
				StoryID:      story.ID,
				ParentTaskID: t.ID,
				Agent:        task.AgentConfig{Type: "claude", Instructions: sub.Instructions},
				Priority:     task.PriorityNormal,
				Tags:         []string{},
				DependsOn:    []string{},
				Retry:        task.RetryConfig{MaxAttempts: 1, Backoff: "exponential"},
				State:        task.StatePending,
				CreatedAt:    time.Now().UTC(),
				UpdatedAt:    time.Now().UTC(),
			}
			if prevSubtaskID != "" {
				st.DependsOn = []string{prevSubtaskID}
			}
			if err := s.store.CreateTask(st); err != nil {
				writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
				return
			}
			prevSubtaskID = st.ID
		}
		prevTaskID = t.ID
	}

	// Create the story branch (non-fatal if it fails).
	if input.BranchName != "" && input.ProjectID != "" {
		if proj, err := s.store.GetProject(input.ProjectID); err == nil && proj.LocalPath != "" {
			if err := createStoryBranch(proj.LocalPath, input.BranchName); err != nil {
				s.logger.Warn("story approve: failed to create branch", "error", err, "branch", input.BranchName)
			}
		}
	}

	writeJSON(w, http.StatusCreated, map[string]interface{}{
		"story":    story,
		"task_ids": taskIDs,
	})
}

// handleStoryDeploymentStatus aggregates the deployment status across all tasks in a story.
// GET /api/stories/{id}/deployment-status
func (s *Server) handleStoryDeploymentStatus(w http.ResponseWriter, r *http.Request) {
	id := r.PathValue("id")

	story, err := s.store.GetStory(id)
	if err != nil {
		writeJSON(w, http.StatusNotFound, map[string]string{"error": "story not found"})
		return
	}

	tasks, err := s.store.ListTasksByStory(id)
	if err != nil {
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
		return
	}

	// Collect all commits from the latest execution of each task.
	var allCommits []task.GitCommit
	for _, t := range tasks {
		exec, err := s.store.GetLatestExecution(t.ID)
		if err != nil {
			if err == sql.ErrNoRows {
				continue
			}
			writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
			return
		}
		allCommits = append(allCommits, exec.Commits...)
	}

	// Determine project remote URL for the deployment check.
	projectRemoteURL := ""
	if story.ProjectID != "" {
		if proj, err := s.store.GetProject(story.ProjectID); err == nil {
			projectRemoteURL = proj.RemoteURL
		}
	}

	status := deployment.Check(allCommits, projectRemoteURL)
	writeJSON(w, http.StatusOK, status)
}