package tui

import (
    "context"
    "encoding/json"
    "os"
    "path/filepath"
    "strings"

    "ai-agent/internal/command"
    "ai-agent/internal/config"
    "ai-agent/internal/mcp"
)

type Completion struct {
    Label       string
    Insert      string
    Category    string
    Description string
    Index       int
}

type Completer struct {
    commands       []*command.Command
    models         []string
    skills         []string
    agents         []string
    workDir        string
    registry       *mcp.Registry
    ignorePatterns *config.IgnorePatterns
}

func NewCompleter(cmdReg *command.Registry, models, skills, agents []string, registry *mcp.Registry) *Completer {
    workDir, _ := os.Getwd()
    return &Completer{
        commands: cmdReg.All(),
        models:   models,
        skills:   skills,
        agents:   agents,
        workDir:  workDir,
        registry: registry,
    }
}

func (c *Completer) Complete(input string) []Completion {
    var completions []Completion

    if strings.HasPrefix(input, "/") {
        completions = c.completeCommand(input)
    } else if strings.HasPrefix(input, "@") {
        completions = c.completeAgentOrFile(input)
    } else if strings.HasPrefix(input, "#") {
        completions = c.completeSkill(input)
    }

    return completions
}

func (c *Completer) completeCommand(input string) []Completion {
    var completions []Completion
    input = strings.TrimPrefix(input, "/")

    for _, cmd := range c.commands {
        if strings.HasPrefix(cmd.Name, input) {
            comp := Completion{
                Label:    "/" + cmd.Name,
                Insert:   "/" + cmd.Name + " ",
                Category: "command",
            }
            if cmd.Usage != "" {
                parts := strings.Fields(cmd.Usage)
                if len(parts) > 1 {
                    comp.Label = "/" + cmd.Name + " " + parts[1]
                }
            }
            completions = append(completions, comp)
        }

        for _, alias := range cmd.Aliases {
            if strings.HasPrefix(alias, input) {
                completions = append(completions, Completion{
                    Label:    "/" + alias,
                    Insert:   "/" + alias + " ",
                    Category: "command",
                })
            }
        }
    }

    return completions
}

func (c *Completer) completeAgentOrFile(input string) []Completion {
    var completions []Completion
    input = strings.TrimPrefix(input, "@")

    // Always show agents first
    for _, agent := range c.agents {
        if strings.HasPrefix(agent, input) {
            completions = append(completions, Completion{
                Label:    "@" + agent,
                Insert:   "@" + agent + " ",
                Category: "agent",
            })
        }
    }

    // Always append file results (not just when no agents match)
    completions = append(completions, c.completeFile(input)...)

    return completions
}

func (c *Completer) completeFile(input string) []Completion {
    var completions []Completion

    // Determine the directory to list
    dir := c.workDir
    if strings.Contains(input, "/") {
        // User is typing a path
        lastSlash := strings.LastIndex(input, "/")
        dirPart := input[:lastSlash]
        if !strings.HasPrefix(dirPart, "/") {
            dirPart = filepath.Join(c.workDir, dirPart)
        }
        if info, err := os.Stat(dirPart); err == nil && info.IsDir() {
            dir = dirPart
        }
    }

    // Read directory entries
    entries, err := os.ReadDir(dir)
    if err != nil {
        return completions
    }

    prefix := input
    if strings.Contains(input, "/") {
        prefix = input[strings.LastIndex(input, "/")+1:]
    }

    for _, entry := range entries {
        name := entry.Name()
        // Skip hidden files unless user explicitly types .
        if strings.HasPrefix(name, ".") && !strings.HasPrefix(prefix, ".") {
            continue
        }
        // Skip entries matching ignore patterns.
        if c.ignorePatterns.Match(name) {
            continue
        }

        if strings.HasPrefix(name, prefix) {
            isDir := entry.IsDir()
            displayName := name
            insertName := name

            if isDir {
                displayName += "/"
                insertName += "/"
            }

            // Build full path relative to input
            if strings.Contains(input, "/") {
                dirPath := input[:strings.LastIndex(input, "/")+1]
                displayName = dirPath + displayName
                insertName = dirPath + insertName
            } else if dir != c.workDir {
                relPath, _ := filepath.Rel(c.workDir, dir)
                if relPath != "." {
                    displayName = relPath + "/" + name
                    if isDir {
                        displayName += "/"
                    } else {
                        insertName = relPath + "/" + insertName
                    }
                }
            }

            category := "file"
            if isDir {
                category = "folder"
            }

            completions = append(completions, Completion{
                Label:    "@" + displayName,
                Insert:   "@" + insertName + " ",
                Category: category,
            })
        }
    }

    return completions
}

// CompleteFilePath lists directory contents at a given relative path.
// Used for folder drill-down in the completion modal.
func (c *Completer) CompleteFilePath(relPath string) []Completion {
    var completions []Completion

    dir := filepath.Join(c.workDir, relPath)
    entries, err := os.ReadDir(dir)
    if err != nil {
        return completions
    }

    for _, entry := range entries {
        name := entry.Name()
        if strings.HasPrefix(name, ".") {
            continue
        }
        // Skip entries matching ignore patterns.
        if c.ignorePatterns.Match(name) {
            continue
        }

        isDir := entry.IsDir()
        displayName := name
        insertPath := relPath
        if insertPath != "" && !strings.HasSuffix(insertPath, "/") {
            insertPath += "/"
        }
        insertPath += name

        if isDir {
            displayName += "/"
        }

        category := "file"
        if isDir {
            category = "folder"
        }

        completions = append(completions, Completion{
            Label:    displayName,
            Insert:   "@" + insertPath + " ",
            Category: category,
        })
    }

    return completions
}

func (c *Completer) completeSkill(input string) []Completion {
    var completions []Completion
    input = strings.TrimPrefix(input, "#")

    for _, skill := range c.skills {
        if strings.HasPrefix(skill, input) {
            completions = append(completions, Completion{
                Label:    "#" + skill,
                Insert:   "#" + skill + " ",
                Category: "skill",
            })
        }
    }

    return completions
}

// FilterCompletions filters completions by case-insensitive substring match on Label.
func FilterCompletions(items []Completion, query string) []Completion {
    if query == "" {
        return items
    }
    q := strings.ToLower(query)
    var filtered []Completion
    for _, item := range items {
        if strings.Contains(strings.ToLower(item.Label), q) {
            filtered = append(filtered, item)
        }
    }
    return filtered
}

// SearchFiles performs an async vecgrep search via the MCP registry.
func (c *Completer) SearchFiles(ctx context.Context, query string) []Completion {
    if c.registry == nil || query == "" {
        return nil
    }

    result, err := c.registry.CallTool(ctx, "vecgrep_search", map[string]any{
        "query": query,
        "limit": 10,
    })
    if err != nil {
        return nil
    }

    var results []Completion
    // Parse the result content as JSON array of file paths or objects
    var searchResults []struct {
        Path  string  `json:"path"`
        Score float64 `json:"score"`
    }
    if err := json.Unmarshal([]byte(result.Content), &searchResults); err != nil {
        // Try as simple string lines
        for _, line := range strings.Split(result.Content, "\n") {
            line = strings.TrimSpace(line)
            if line == "" {
                continue
            }
            results = append(results, Completion{
                Label:       "@" + line,
                Insert:      "@" + line + " ",
                Category:    "search_result",
                Description: "vecgrep match",
            })
        }
        return results
    }

    for _, sr := range searchResults {
        results = append(results, Completion{
            Label:       "@" + sr.Path,
            Insert:      "@" + sr.Path + " ",
            Category:    "search_result",
            Description: "vecgrep match",
        })
    }
    return results
}

func (c *Completer) UpdateModels(models []string) {
    c.models = models
}

func (c *Completer) UpdateSkills(skills []string) {
    c.skills = skills
}

func (c *Completer) UpdateAgents(agents []string) {
    c.agents = agents
}

// SetIgnorePatterns sets the ignore patterns used to filter file completions.
func (c *Completer) SetIgnorePatterns(patterns *config.IgnorePatterns) {
    c.ignorePatterns = patterns
}