package api

import (
	"errors"
	"fmt"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/kandev/kandev/internal/agentctl/server/process"
	"go.uber.org/zap"
)

// GitPullRequest for POST /api/v1/git/pull
type GitPullRequest struct {
	Rebase bool `json:"rebase"`
}

// GitPushRequest for POST /api/v1/git/push
type GitPushRequest struct {
	Force       bool `json:"force"`
	SetUpstream bool `json:"set_upstream"`
}

// GitRebaseRequest for POST /api/v1/git/rebase
type GitRebaseRequest struct {
	BaseBranch string `json:"base_branch"`
}

// GitMergeRequest for POST /api/v1/git/merge
type GitMergeRequest struct {
	BaseBranch string `json:"base_branch"`
}

// GitAbortRequest for POST /api/v1/git/abort
type GitAbortRequest struct {
	Operation string `json:"operation"` // "merge" or "rebase"
}

// GitCommitRequest for POST /api/v1/git/commit
type GitCommitRequest struct {
	Message  string `json:"message"`
	StageAll bool   `json:"stage_all"`
	Amend    bool   `json:"amend"`
}

// GitRenameBranchRequest for POST /api/v1/git/rename-branch
type GitRenameBranchRequest struct {
	NewName string `json:"new_name"`
}

// GitStageRequest for POST /api/v1/git/stage
type GitStageRequest struct {
	Paths []string `json:"paths"` // Empty = stage all
}

// GitUnstageRequest for POST /api/v1/git/unstage
type GitUnstageRequest struct {
	Paths []string `json:"paths"` // Empty = unstage all
}

// GitDiscardRequest for POST /api/v1/git/discard
type GitDiscardRequest struct {
	Paths []string `json:"paths"` // Required - files to discard
}

// GitShowCommitRequest for GET /api/v1/git/commit/:sha
type GitShowCommitRequest struct {
	CommitSHA string `uri:"sha" binding:"required"`
}

// GitRevertCommitRequest for POST /api/v1/git/revert-commit
type GitRevertCommitRequest struct {
	CommitSHA string `json:"commit_sha"`
}

// GitCreatePRRequest for POST /api/v1/git/create-pr
type GitCreatePRRequest struct {
	Title      string `json:"title"`
	Body       string `json:"body"`
	BaseBranch string `json:"base_branch"`
	Draft      bool   `json:"draft"`
}

// GitResetRequest for POST /api/v1/git/reset
type GitResetRequest struct {
	CommitSHA string `json:"commit_sha"`
	Mode      string `json:"mode"` // "soft", "mixed", or "hard"
}

// GitLogRequest for GET /api/v1/git/log
type GitLogRequest struct {
	Since        string `form:"since"`         // Base commit SHA (exclusive)
	TargetBranch string `form:"target_branch"` // Target branch for merge-base calculation (e.g., "origin/main")
	Limit        int    `form:"limit"`         // Max commits to return
}

// GitCumulativeDiffRequest for GET /api/v1/git/cumulative-diff
type GitCumulativeDiffRequest struct {
	Base string `form:"base" binding:"required"` // Base commit SHA
}

// handleGitPull handles POST /api/v1/git/pull
func (s *Server) handleGitPull(c *gin.Context) {
	var req GitPullRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "pull",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Pull(c.Request.Context(), req.Rebase)
	if err != nil {
		s.handleGitError(c, "pull", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitPush handles POST /api/v1/git/push
func (s *Server) handleGitPush(c *gin.Context) {
	var req GitPushRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "push",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Push(c.Request.Context(), req.Force, req.SetUpstream)
	if err != nil {
		s.handleGitError(c, "push", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitRebase handles POST /api/v1/git/rebase
func (s *Server) handleGitRebase(c *gin.Context) {
	var req GitRebaseRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "rebase",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if req.BaseBranch == "" {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "rebase",
			Error:     "base_branch is required",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Rebase(c.Request.Context(), req.BaseBranch)
	if err != nil {
		s.handleGitError(c, "rebase", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitMerge handles POST /api/v1/git/merge
func (s *Server) handleGitMerge(c *gin.Context) {
	var req GitMergeRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "merge",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if req.BaseBranch == "" {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "merge",
			Error:     "base_branch is required",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Merge(c.Request.Context(), req.BaseBranch)
	if err != nil {
		s.handleGitError(c, "merge", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitAbort handles POST /api/v1/git/abort
func (s *Server) handleGitAbort(c *gin.Context) {
	var req GitAbortRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "abort",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if req.Operation != "merge" && req.Operation != "rebase" {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "abort",
			Error:     "operation must be 'merge' or 'rebase'",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Abort(c.Request.Context(), req.Operation)
	if err != nil {
		s.handleGitError(c, "abort", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitCommit handles POST /api/v1/git/commit
func (s *Server) handleGitCommit(c *gin.Context) {
	var req GitCommitRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "commit",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if req.Message == "" {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "commit",
			Error:     "message is required",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Commit(c.Request.Context(), req.Message, req.StageAll, req.Amend)
	if err != nil {
		s.handleGitError(c, "commit", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitRenameBranch handles POST /api/v1/git/rename-branch
func (s *Server) handleGitRenameBranch(c *gin.Context) {
	var req GitRenameBranchRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "rename_branch",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if req.NewName == "" {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "rename_branch",
			Error:     "new_name is required",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.RenameBranch(c.Request.Context(), req.NewName)
	if err != nil {
		s.handleGitError(c, "rename_branch", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitStage handles POST /api/v1/git/stage
func (s *Server) handleGitStage(c *gin.Context) {
	var req GitStageRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "stage",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Stage(c.Request.Context(), req.Paths)
	if err != nil {
		s.handleGitError(c, "stage", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitUnstage handles POST /api/v1/git/unstage
func (s *Server) handleGitUnstage(c *gin.Context) {
	var req GitUnstageRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "unstage",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Unstage(c.Request.Context(), req.Paths)
	if err != nil {
		s.handleGitError(c, "unstage", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitDiscard handles POST /api/v1/git/discard
func (s *Server) handleGitDiscard(c *gin.Context) {
	var req GitDiscardRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "discard",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if len(req.Paths) == 0 {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "discard",
			Error:     "paths are required",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Discard(c.Request.Context(), req.Paths)
	if err != nil {
		s.handleGitError(c, "discard", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitCreatePR handles POST /api/v1/git/create-pr
func (s *Server) handleGitCreatePR(c *gin.Context) {
	var req GitCreatePRRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.PRCreateResult{
			Success: false,
			Error:   "invalid request: " + err.Error(),
		})
		return
	}

	if req.Title == "" {
		c.JSON(http.StatusBadRequest, process.PRCreateResult{
			Success: false,
			Error:   "title is required",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.CreatePR(c.Request.Context(), req.Title, req.Body, req.BaseBranch, req.Draft)
	if err != nil {
		if errors.Is(err, process.ErrOperationInProgress) {
			c.JSON(http.StatusConflict, process.PRCreateResult{
				Success: false,
				Error:   "another git operation is already in progress",
			})
			return
		}
		s.logger.Error("git create-pr failed", zap.Error(err))
		c.JSON(http.StatusInternalServerError, process.PRCreateResult{
			Success: false,
			Error:   err.Error(),
		})
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitRevertCommit handles POST /api/v1/git/revert-commit
func (s *Server) handleGitRevertCommit(c *gin.Context) {
	var req GitRevertCommitRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "revert_commit",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if req.CommitSHA == "" {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "revert_commit",
			Error:     "commit_sha is required",
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.RevertCommit(c.Request.Context(), req.CommitSHA)
	if err != nil {
		s.handleGitError(c, "revert_commit", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitShowCommit handles GET /api/v1/git/commit/:sha
func (s *Server) handleGitShowCommit(c *gin.Context) {
	var req GitShowCommitRequest
	if err := c.ShouldBindUri(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.CommitDiffResult{
			Success: false,
			Error:   "invalid request: " + err.Error(),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.ShowCommit(c.Request.Context(), req.CommitSHA)
	if err != nil {
		s.logger.Error("git show commit failed", zap.String("commit_sha", req.CommitSHA), zap.Error(err))
		c.JSON(http.StatusInternalServerError, process.CommitDiffResult{
			Success:   false,
			CommitSHA: req.CommitSHA,
			Error:     err.Error(),
		})
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitReset handles POST /api/v1/git/reset
func (s *Server) handleGitReset(c *gin.Context) {
	var req GitResetRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "reset",
			Error:     "invalid request: " + err.Error(),
		})
		return
	}

	if req.CommitSHA == "" {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "reset",
			Error:     "commit_sha is required",
		})
		return
	}

	if req.Mode == "" {
		req.Mode = "mixed"
	}
	validModes := map[string]bool{"soft": true, "mixed": true, "hard": true}
	if !validModes[req.Mode] {
		c.JSON(http.StatusBadRequest, process.GitOperationResult{
			Success:   false,
			Operation: "reset",
			Error:     fmt.Sprintf("invalid reset mode: %s (must be soft, mixed, or hard)", req.Mode),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.Reset(c.Request.Context(), req.CommitSHA, req.Mode)
	if err != nil {
		s.handleGitError(c, "reset", err)
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitLog handles GET /api/v1/git/log
func (s *Server) handleGitLog(c *gin.Context) {
	var req GitLogRequest
	if err := c.ShouldBindQuery(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.GitLogResult{
			Success: false,
			Error:   "invalid request: " + err.Error(),
		})
		return
	}

	// Bound limit to prevent expensive history scans
	const (
		defaultLogLimit = 100
		maxLogLimit     = 500
	)
	limit := req.Limit
	if limit <= 0 {
		limit = defaultLogLimit
	} else if limit > maxLogLimit {
		c.JSON(http.StatusBadRequest, process.GitLogResult{
			Success: false,
			Error:   fmt.Sprintf("limit must be between 1 and %d", maxLogLimit),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()

	// If target_branch is provided, compute merge-base dynamically.
	// This ensures we only show commits not yet merged into the target branch,
	// which is accurate even after rebases.
	baseCommit := req.Since
	if req.TargetBranch != "" {
		mergeBase, err := gitOp.GetMergeBase(c.Request.Context(), "HEAD", req.TargetBranch)
		if err != nil {
			s.logger.Warn("failed to compute merge-base, falling back to since",
				zap.String("target_branch", req.TargetBranch),
				zap.Error(err))
			// Fall back to the provided base commit
		} else if mergeBase != "" {
			baseCommit = mergeBase
		}
	}

	result, err := gitOp.GetLog(c.Request.Context(), baseCommit, limit)
	if err != nil {
		s.logger.Error("git log failed", zap.Error(err))
		c.JSON(http.StatusInternalServerError, process.GitLogResult{
			Success: false,
			Error:   err.Error(),
		})
		return
	}

	c.JSON(http.StatusOK, result)
}

// handleGitCumulativeDiff handles GET /api/v1/git/cumulative-diff
func (s *Server) handleGitCumulativeDiff(c *gin.Context) {
	var req GitCumulativeDiffRequest
	if err := c.ShouldBindQuery(&req); err != nil {
		c.JSON(http.StatusBadRequest, process.CumulativeDiffResult{
			Success: false,
			Error:   "invalid request: " + err.Error(),
		})
		return
	}

	gitOp := s.procMgr.GitOperator()
	result, err := gitOp.GetCumulativeDiff(c.Request.Context(), req.Base)
	if err != nil {
		s.logger.Error("git cumulative diff failed", zap.String("base", req.Base), zap.Error(err))
		c.JSON(http.StatusInternalServerError, process.CumulativeDiffResult{
			Success: false,
			Error:   err.Error(),
		})
		return
	}

	c.JSON(http.StatusOK, result)
}

// GitStatusResult represents the result of a git status query.
type GitStatusResult struct {
	Success         bool                   `json:"success"`
	Branch          string                 `json:"branch"`
	RemoteBranch    string                 `json:"remote_branch"`
	HeadCommit      string                 `json:"head_commit"`
	BaseCommit      string                 `json:"base_commit"` // Merge-base with origin branch
	Ahead           int                    `json:"ahead"`
	Behind          int                    `json:"behind"`
	Modified        []string               `json:"modified"`
	Added           []string               `json:"added"`
	Deleted         []string               `json:"deleted"`
	Untracked       []string               `json:"untracked"`
	Renamed         []string               `json:"renamed"`
	Files           map[string]interface{} `json:"files"`
	Timestamp       string                 `json:"timestamp"`
	BranchAdditions int                    `json:"branch_additions,omitempty"`
	BranchDeletions int                    `json:"branch_deletions,omitempty"`
	Error           string                 `json:"error,omitempty"`
}

// handleGitStatus handles GET /api/v1/git/status
func (s *Server) handleGitStatus(c *gin.Context) {
	wt := s.procMgr.GetWorkspaceTracker()
	if wt == nil {
		c.JSON(http.StatusInternalServerError, GitStatusResult{
			Success: false,
			Error:   "workspace tracker not available",
		})
		return
	}

	status, err := wt.GetCurrentGitStatus(c.Request.Context())
	if err != nil {
		s.logger.Error("git status failed", zap.Error(err))
		c.JSON(http.StatusInternalServerError, GitStatusResult{
			Success: false,
			Error:   err.Error(),
		})
		return
	}

	// Convert Files map to interface{} map for JSON serialization
	filesMap := make(map[string]interface{}, len(status.Files))
	for k, v := range status.Files {
		filesMap[k] = v
	}

	c.JSON(http.StatusOK, GitStatusResult{
		Success:         true,
		Branch:          status.Branch,
		RemoteBranch:    status.RemoteBranch,
		HeadCommit:      status.HeadCommit,
		BaseCommit:      status.BaseCommit,
		Ahead:           status.Ahead,
		Behind:          status.Behind,
		Modified:        status.Modified,
		Added:           status.Added,
		Deleted:         status.Deleted,
		Untracked:       status.Untracked,
		Renamed:         status.Renamed,
		Files:           filesMap,
		Timestamp:       status.Timestamp.Format("2006-01-02T15:04:05.000Z07:00"),
		BranchAdditions: status.BranchAdditions,
		BranchDeletions: status.BranchDeletions,
	})
}

// handleGitError handles errors from git operations.
func (s *Server) handleGitError(c *gin.Context, operation string, err error) {
	if errors.Is(err, process.ErrOperationInProgress) {
		c.JSON(http.StatusConflict, process.GitOperationResult{
			Success:   false,
			Operation: operation,
			Error:     "another git operation is already in progress",
		})
		return
	}

	s.logger.Error("git operation failed", zap.String("operation", operation), zap.Error(err))
	c.JSON(http.StatusInternalServerError, process.GitOperationResult{
		Success:   false,
		Operation: operation,
		Error:     err.Error(),
	})
}