package handlers

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"

	"github.com/HoHD/PR-Helper/models"
	"github.com/HoHD/PR-Helper/services"
	"github.com/gin-gonic/gin"
)

type ReviewHandler struct {
	db *sql.DB
}

func NewReviewHandler(db *sql.DB) *ReviewHandler {
	return &ReviewHandler{db: db}
}

// Review handles POST /api/repos/:id/review — SSE streaming AI code review.
func (h *ReviewHandler) Review(c *gin.Context) {
	id := c.Param("id")

	// Get repo info
	var localPath string
	err := h.db.QueryRow(`SELECT local_path FROM repositories WHERE id = ?`, id).Scan(&localPath)
	if err == sql.ErrNoRows {
		c.JSON(http.StatusNotFound, gin.H{"error": "repository not found"})
		return
	}
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	// Parse request
	var req struct {
		Base string `json:"base" binding:"required"`
		Head string `json:"head" binding:"required"`
		TopN *int   `json:"top_n"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "base and head are required"})
		return
	}

	// Determine Top-N: request value > settings default (20)
	topN := 20
	if req.TopN != nil {
		topN = *req.TopN
	} else {
		var topNStr string
		h.db.QueryRow(`SELECT value FROM settings WHERE key = 'review.top_n'`).Scan(&topNStr)
		if topNStr != "" {
			if n, err := strconv.Atoi(topNStr); err == nil && n > 0 {
				topN = n
			}
		}
	}

	// Set SSE headers
	c.Header("Content-Type", "text/event-stream")
	c.Header("Cache-Control", "no-cache")
	c.Header("Connection", "keep-alive")
	c.Header("X-Accel-Buffering", "no")
	c.Status(http.StatusOK)

	flusher, ok := c.Writer.(http.Flusher)
	if !ok {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "streaming not supported"})
		return
	}

	sendEvent := func(event string, data interface{}) {
		jsonData, _ := json.Marshal(data)
		fmt.Fprintf(c.Writer, "event: %s\ndata: %s\n\n", event, jsonData)
		flusher.Flush()
	}

	// Update last_used
	h.db.Exec(`UPDATE repositories SET last_used = datetime('now') WHERE id = ?`, id)

	// Run AI review
	reviewResult, err := services.GenerateReview(h.db, localPath, req.Base, req.Head, topN, sendEvent)
	if err != nil {
		sendEvent("error", map[string]interface{}{"message": err.Error()})
		return
	}

	// Save analysis to DB with full review result
	resultJSON, _ := json.Marshal(reviewResult)
	res, err := h.db.Exec(`INSERT INTO analyses (repo_id, type, base_ref, head_ref, result) VALUES (?, 'code_review', ?, ?, ?)`,
		id, req.Base, req.Head, string(resultJSON))
	if err == nil {
		analysisID, _ := res.LastInsertId()
		sendEvent("analysis_saved", map[string]interface{}{
			"analysis_id": analysisID,
		})
	}
}

// SaveNotes handles POST /api/repos/:id/review/notes — upsert a review note.
func (h *ReviewHandler) SaveNotes(c *gin.Context) {
	var req struct {
		AnalysisID int64  `json:"analysis_id" binding:"required"`
		Scope      string `json:"scope" binding:"required"`
		ScopeKey   string `json:"scope_key"`
		Content    string `json:"content"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "analysis_id and scope are required"})
		return
	}

	// Validate scope
	switch req.Scope {
	case "overall", "file", "suggestion":
		// valid
	default:
		c.JSON(http.StatusBadRequest, gin.H{"error": "scope must be overall, file, or suggestion"})
		return
	}

	note, err := services.SaveNote(h.db, req.AnalysisID, req.Scope, req.ScopeKey, req.Content)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	c.JSON(http.StatusOK, note)
}

// GetNotes handles GET /api/repos/:id/review/notes — list review notes for an analysis.
func (h *ReviewHandler) GetNotes(c *gin.Context) {
	analysisIDStr := c.Query("analysis_id")
	if analysisIDStr == "" {
		c.JSON(http.StatusBadRequest, gin.H{"error": "analysis_id query parameter is required"})
		return
	}

	analysisID, err := strconv.ParseInt(analysisIDStr, 10, 64)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid analysis_id"})
		return
	}

	scope := c.Query("scope") // optional filter

	notes, err := services.GetNotes(h.db, analysisID, scope)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	if notes == nil {
		notes = []models.ReviewNote{}
	}
	c.JSON(http.StatusOK, notes)
}

// ListReviews handles GET /api/repos/:id/review/analyses — list past code review analyses.
func (h *ReviewHandler) ListReviews(c *gin.Context) {
	id := c.Param("id")

	rows, err := h.db.Query(`SELECT id, base_ref, head_ref, result, created_at FROM analyses WHERE repo_id = ? AND type = 'code_review' ORDER BY created_at DESC`, id)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}
	defer rows.Close()

	var analyses []map[string]interface{}
	for rows.Next() {
		var aid int64
		var baseRef, headRef, result string
		var createdAt string
		if err := rows.Scan(&aid, &baseRef, &headRef, &result, &createdAt); err != nil {
			continue
		}
		analyses = append(analyses, map[string]interface{}{
			"id":         aid,
			"base_ref":   baseRef,
			"head_ref":   headRef,
			"created_at": createdAt,
		})
	}

	if analyses == nil {
		analyses = []map[string]interface{}{}
	}
	c.JSON(http.StatusOK, analyses)
}

// GetReview handles GET /api/repos/:id/review/analyses/:aid — get a single review with full result.
func (h *ReviewHandler) GetReview(c *gin.Context) {
	aid := c.Param("aid")

	var result, baseRef, headRef, createdAt string
	err := h.db.QueryRow(`SELECT result, base_ref, head_ref, created_at FROM analyses WHERE id = ? AND type = 'code_review'`, aid).Scan(&result, &baseRef, &headRef, &createdAt)
	if err == sql.ErrNoRows {
		c.JSON(http.StatusNotFound, gin.H{"error": "analysis not found"})
		return
	}
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	// Parse the result JSON to include structured data
	var reviewResult interface{}
	if err := json.Unmarshal([]byte(result), &reviewResult); err != nil {
		reviewResult = result
	}

	c.JSON(http.StatusOK, gin.H{
		"id":         aid,
		"base_ref":   baseRef,
		"head_ref":   headRef,
		"created_at": createdAt,
		"result":     reviewResult,
	})
}

// GeneratePDF handles POST /api/repos/:id/review/pdf — generate and download a PDF report.
func (h *ReviewHandler) GeneratePDF(c *gin.Context) {
	id := c.Param("id")

	// Get repo info
	var repoURL string
	err := h.db.QueryRow(`SELECT url FROM repositories WHERE id = ?`, id).Scan(&repoURL)
	if err == sql.ErrNoRows {
		c.JSON(http.StatusNotFound, gin.H{"error": "repository not found"})
		return
	}
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	// Parse request
	var req struct {
		AnalysisID int64  `json:"analysis_id" binding:"required"`
		Base       string `json:"base"`
		Head       string `json:"head"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"error": "analysis_id is required"})
		return
	}

	// Load the analysis result
	var analysisResult, baseRef, headRef string
	var createdAt string
	err = h.db.QueryRow(`SELECT result, base_ref, head_ref, created_at FROM analyses WHERE id = ?`, req.AnalysisID).Scan(&analysisResult, &baseRef, &headRef, &createdAt)
	if err == sql.ErrNoRows {
		c.JSON(http.StatusNotFound, gin.H{"error": "analysis not found"})
		return
	}
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	// Load all notes for this analysis
	notes, err := services.GetNotes(h.db, req.AnalysisID, "")
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
		return
	}

	// Build report data
	reportData := services.ReportData{
		RepoURL:     repoURL,
		BaseRef:     baseRef,
		HeadRef:     headRef,
		ReviewedAt:  createdAt,
		AnalysisID:  req.AnalysisID,
		Result:      analysisResult,
		Notes:       notes,
	}

	// Generate PDF
	pdfBytes, err := services.GeneratePDFReport(reportData)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "PDF generation failed: " + err.Error()})
		return
	}

	// Return PDF as download
	filename := fmt.Sprintf("pr-helper-review-%s.pdf", createdAt[:10])
	c.Header("Content-Type", "application/pdf")
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
	c.Data(http.StatusOK, "application/pdf", pdfBytes)
}