#!/usr/bin/env nu
# Docker Compose Build File Generator
# Generates docker-compose.build.yml from Nickel template for parallel BuildKit builds
#
# Usage:
#   docker-generate-compose.nu                    # Generate with default registry (localhost:5000)
#   docker-generate-compose.nu --registry ghcr.io # Generate with custom registry
#
# Environment:
#   PROVISIONING_ROOT - Optional: override project root detection
#
# Patterns:
#   - Result pattern (NO try-catch)
#   - Pipeline let binding (Nushell 0.110.0+)
#   - Guards for validation

# Search up directory tree for provisioning root (helper)
def search-up-for-provisioning [dir: string]: nothing -> string {
    if ($"($dir)/schemas/platform" | path exists) {
        $dir
    } else {
        let parent = ($dir | path dirname)
        if $parent == $dir {
            ""
        } else {
            search-up-for-provisioning $parent
        }
    }
}

# Detect provisioning project root
# Follows same pattern as platform-generate-manifests.nu
def get-provisioning-root []: nothing -> string {
    # 1. Check PROVISIONING environment variable (standard)
    if ($env.PROVISIONING? != null) {
        return $env.PROVISIONING
    }

    # 2. Check PROVISIONING_ROOT (alternative)
    if ($env.PROVISIONING_ROOT? != null) {
        return $env.PROVISIONING_ROOT
    }

    # 3. Check if we're in provisioning/ directory
    let cwd = (pwd)
    if ($cwd | path basename) == "provisioning" {
        # We're inside provisioning/, use current dir
        if ("schemas/platform" | path exists) {
            return "."
        }
    }

    # 4. Check if provisioning/ exists as subdirectory
    if ("provisioning/schemas/platform" | path exists) {
        return "provisioning"
    }

    # 5. Search up the directory tree
    let found = (search-up-for-provisioning $cwd)
    if $found != "" {
        return $found
    }

    # 6. Fallback to current directory
    pwd
}

# Generate docker-compose.build.yml from Nickel template
def main [
    --registry: string = "localhost:5000",  # Docker registry for image tags
    --output: string = "",                   # Output file path (default: docker-compose.build.yml)
]: nothing -> record<ok: bool, err: string, path: string> {
    # Detect provisioning root
    let prov_root = (get-provisioning-root)

    # Construct paths
    let template_file = $"($prov_root)/schemas/platform/templates/docker/docker-compose.build.yml.ncl"
    let output_file = if ($output | is-empty) {
        $"($prov_root)/docker-compose.build.yml"
    } else {
        $output
    }

    # Guard: Check template file exists
    if not ($template_file | path exists) {
        return {
            ok: false,
            err: $"Template file not found: ($template_file)",
            path: ""
        }
    }

    # Execute nickel export
    # Note: Registry customization must be done by editing the template or the generated file
    let result = (
        nickel export
            --format yaml
            $template_file
        | complete
    )

    if $result.exit_code != 0 {
        return {
            ok: false,
            err: $"Nickel export failed: ($result.stderr)",
            path: ""
        }
    }

    let compose_yaml = $result.stdout

    # Check if generation succeeded
    if ($compose_yaml | is-empty) {
        return {
            ok: false,
            err: "Generated docker-compose.yml is empty",
            path: ""
        }
    }

    # Write docker-compose.build.yml
    $compose_yaml | save --force $output_file

    # Return success
    {
        ok: true,
        err: "",
        path: $output_file
    }
}